WO2017096562A1 - Method for manufacturing carbonate diester - Google Patents

Abstract

The present invention discloses a method for manufacturing a carbonate diester, wherein a liquid catalyst used in the production of the carbonate diester from reaction of an alcohol, carbon monoxide and oxygen is included. The liquid catalyst comprises a copper compound, a nitrogen-containing cyclic compound and a glycol ether, wherein the copper compound is in a dissolved state in the solution constituting the liquid catalyst. The liquid catalyst of the present invention can selectively promote the reaction that generates the carbonate diester and allow easy recovery of the carbonate diester from the resulting products of the reaction. The reaction liquid obtained with the liquid catalyst of the present invention is a homogeneous solution free of solids. Thus, it is possible to directly distill the solution and easily obtain the carbon diester in high purity.

Description

Method for producing carbonic acid diester Technical field

The invention relates to a method for producing a carbonic acid diester, and belongs to the technical field of chemical materials.

Background technique

In addition to being used as a raw material for medicines and pesticides, carbonic acid diesters such as dimethyl carbonate have also been used as gasoline additives (octane boosters) in recent years, or as a reaction raw material, instead of being used as a raw material for producing various types of carbonates. Phosgene has attracted people's attention.

Heretofore, as a method for producing a carbonic acid diester, a method of reacting with phosgene and an alcohol is known, and is actually an industrial method. However, due to the problem of corrosion of the device material by the by-product hydrochloric acid in this method, and the toxicity of phosgene, etc., a non-phosgene manufacturing technique that does not use phosgene has been sought.

In order to achieve the above object, dimethyl carbonate is produced by the oxidative carbonylation reaction of methanol using copper (I) chloride as a catalyst, and has been industrialized. This is the only non-phosgene device. However, this method still fails to completely solve the problem of corrosion of the device material by the by-product hydrochloric acid. Therefore, it is necessary to install a glass lining on the inner surface of the reactor, which hinders the enlargement of the device. Further, in this method, in order to obtain a preferable reaction rate, it is necessary to use a copper salt having a high concentration of 14% by weight or more, so that a so-called cement-containing slurry is formed due to the presence of solids in the reaction liquid. In order to separate solids from the resulting carbonate, special process problems such as additional membrane separation or centrifugation must be considered. Moreover, there is a problem that the price of the device is increased due to the necessity of heat resistance, pressure resistance, and corrosion resistance.

In order to avoid the above problems, in order to avoid muddy reaction system, various additives are added to the reaction system to form a uniform reaction system, and a carbonic acid diester production method of a uniform reaction system is developed.

For example, a U.S. patent has developed a test method for the oxidative carbonylation of methanol using a catalyst formed from copper chloride and a nitrogen-containing compound. However, when such a catalyst is used, since the solubility of copper chloride is low, it is necessary to limit the catalyst concentration, and thus there is no practical value. Further, Japanese Patent No. 62-81356 discloses the addition of a pyridine compound to the reaction system, at which time a uniform reaction system is not formed, and the reaction system is still a slurry.

U.S. Patent No. 4,064,242 discloses the use of bis(2,4-pentandinato) copper(II) methoxide-pyridine to achieve a homogeneous system, but the copper compound used in the catalyst is extremely special and has a slow reaction rate and has no practical value.

Further, Japanese Patent Publication No. 5-17410 discloses that an alkaline earth metal hydroxide (Mg(OH)2, etc.) is added to CuCl2 to make the catalyst uniform, and it is possible to suppress the formation of by-product methyl chloride when using cuprous chloride. Disadvantages such as methyl ether, but the use of this catalyst as a catalyst for industrial use is still unsatisfactory.

Japanese Patent Publication No. 6-25105 discloses that a metal halide of titanium, tin, antimony, bismuth, molybdenum or manganese coexists to avoid precipitation of copper (I), but due to the metal halide, there is a by-product of combustion of CO. The tendency to increase CO2 is not very useful.

Among other methods for avoiding mud systems, a well-known method is to form a uniform catalytic system using a lower concentration of CuCl2/PdCl3 (Japanese Patent No. 5-105642, 5-320098, 5-320099, etc.). However, in this method, since the by-product oxalic acid is produced by using Pd, the generated oxalic acid and copper ions react to form insoluble copper oxalate, thereby lowering the catalyst activity.

As another method for avoiding mud formation, a method of carrying out a gas phase reaction using a catalyst in which a copper salt or a complex salt thereof is supported on a solid support is proposed. Such as US patents USP 2, 625, 044 and Japanese Patent No. 2, 256, 651 disclose a method for gas phase reaction using a catalyst comprising copper chloride or a copper-pyridine complex supported on activated carbon, but this method has low selectivity to carbonic acid diester and is accompanied by Halogen splashing causes problems such as a decrease in catalytic activity, which is not a satisfactory method.

Japanese Patent Publication No. 6-21081 also discloses a method of carrying out a reaction using a catalyst in which a copper-triphenylphosphine complex is supported on activated carbon, but at this time, a halogen must be present on the catalyst, and catalytic activity is accompanied by splashing of halogen and hydrogen halide. decline. Further, as a method for regenerating a solid catalyst, a halogen gas and a hydrogen halide gas have been proposed as a treatment method for a regeneration gas (Japanese Patent No. 6-210181, 5-49947, 5-208137), but there is a method for regenerating such a catalyst. The regenerative gas corrodes the reactor, the residual regeneration gas reacts with the raw material alcohol to form a halogenated alkane, and the product carbonic acid diester is hydrolyzed.

Summary of the invention

The object of the present invention is as follows: (1) A liquid catalyst for producing a carbonic acid diester having high selectivity to carbonic acid diester and low corrosivity is provided. (2) A method for producing a carbonic acid diester using the above liquid catalyst. (3) A suitable production apparatus for carrying out a method of producing a carbonic acid diester using the above liquid catalyst is provided.

Other objects of the present invention will be understood and understood from the following description.

The inventors of the present invention have conducted intensive studies to solve the above problems, and have achieved important results, thereby completing the present invention.

a liquid catalyst for use in the production of a carbonic acid diester by reacting an alcohol with carbon monoxide and oxygen in accordance with the present invention, which comprises

(1) Copper compound

(2) cyclic nitrogen-containing compounds and

(3) a glycol ether represented by the following formula (I),

R ¹ O[CH(R ² )CH ₂ O] _n R ³ (I)

Wherein R ¹ represents an alkyl group of ^{1 to} 8 carbon atoms, R ² represents an alkyl group of 1 to 3 carbon atoms or hydrogen, R ³ represents an alkyl group of 1 to 8 carbon atoms or hydrogen, and n represents 1-16. Integer,

A liquid catalyst comprising a solution of the above copper compound in a dissolved state is allowed to react with an alcohol, carbon monoxide and oxygen.

Wherein the cyclic nitrogen-containing compound is a substituted or unsubstituted pyridine compound.

Wherein, the molar ratio of the cyclic nitrogen-containing compound to the copper compound is in the range of 0.5 to 100.

Wherein, the molar ratio of the glycol ether to the copper compound is in the range of 5 to 200.

Preferably, the carbon monoxide is contacted with the liquid catalyst at a partial pressure of carbon monoxide of 50 to 200 ° C and 0.1 to 50 kg/cm ² .

More preferably, the partial pressure of oxygen during the reaction is in the range of from 0.010 to 10 kg/cm ² .

Specifically, the partial pressure of carbon monoxide at the time of the reaction is in the range of 0.1 to 50 kg/cm ² .

More specifically, the reaction temperature is 50 to 200 °C.

In any one of the foregoing liquid catalysts, a process for producing a carbonic acid diester of a reaction solution containing a carbonic acid diester by reacting an alcohol with carbon monoxide and oxygen; and a process for separating a carbonic acid diester of the carbonic acid diester from the reaction solution; A liquid catalyst regeneration process in which a liquid catalyst obtained by separating a carbonic acid diester is contacted with carbon monoxide.

The copper compound includes a copper halide, a mineral acid of copper, an organic acid salt of copper, a complex salt of copper, and the like, and the copper compound may be a monovalent copper (I) compound and/or a divalent copper (II) compound.

The above copper halides include chlorides, bromides and iodides, and specific examples are CuCl, CuCl ₂ , CuBr, CuBr ₂ , CuI and the like.

The above copper mineral acid salt includes a nitrate, a carbonate, a borate, a phosphate, etc., and specific examples thereof include Cu(NO ₃ ) ₂ , CuCO ₃ ·Cu(OH) ₂ ·H ₂ O, CuB ₄ O _{7 .} , CuPO _4, etc.

The copper organic acid salt includes a carboxylate, a sulfonate, a phosphate, a phosphonate, and the like, and specific examples thereof include a formate, an acetate, an oxalate, and the like.

The copper complex salt may be a copper complex salt such as a chain amine such as trimethylamine or a cyclic amine such as pyridine or an organic phosphine compound such as triphenylphosphine as a ligand.

The copper compound used in the present invention is particularly preferably cuprous chloride (CuCl) or a complex thereof from the viewpoints of catalyst activity and selectivity to carbonic acid diester.

In the glycol ether compound represented by the formula (I) used in the invention, R ¹ is an alkyl group of ¹ to 8 carbon atoms, preferably 1 to 4 carbon atoms, more preferably 1 to 2 carbon atoms; R ² is an alkyl group of 1 to 4 carbon atoms or hydrogen, preferably hydrogen or methyl, more preferably hydrogen; R ³ is 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, more preferably 1 An alkyl group of 2 carbon atoms or hydrogen; n is an integer from 1 to 16, preferably from 1 to 6, more preferably from 2 to 4. When the number of carbon atoms of R ¹ exceeds 6, the solubility of the copper compound may decrease. When the number of carbon atoms of R ² exceeds 2, the solubility of the copper compound may decrease, and when the number of carbon atoms of R ³ exceeds 6, There is still a case where the solubility of the copper compound is lowered; in addition, when n exceeds 12, there is a disadvantage that the solubility of the copper compound is lowered and the viscosity of the cuprous catalyst is increased.

The glycol ether used in the present invention is a compound represented by the above formula (I), and a typical glycol ether is 1 mole of methanol, ethanol, propanol and/or butanol and 2 to 12 moles of ethylene oxide and/or a ring. a glycerol monoalkyl ether compound formed by oxypropane; another typical glycol ether compound is substituted with a lower alkyl group such as methyl, ethyl, propyl or butyl to the above-mentioned glycerol monoalkyl ether terminal OH A glycol dialkyl ether compound obtained by H. Further, the above glycol ether compounds may be used singly or in the form of a mixture of two or more.

Such a glycol ether compound has high solubility in CO and oxygen, and high solubility in a complex of copper and a cyclic nitrogen-containing compound, so that precipitation of a copper compound can be avoided. Such glycol ether compounds are easily synthesized by etherification of glycols and alcohols, and are also commercially available. Glycol ether is widely used as a gas absorbent. It has excellent solubility in various gaseous substances, stable chemical properties, no corrosiveness, no formation of insolubles and precipitates, high thermal stability, and poor solvent properties. Low pressure, low solvent loss and other characteristics.

The cyclic nitrogen-containing compound used in the present invention is pyridine or a pyridine compound having a substituent such as an alkyl group, an alkoxy group or a halogen atom which does not impair the reaction of a carbonic acid diester on the pyridine ring, and examples thereof include pyridine. , 2-hydroxypyridine, 2-methylpyridine, 2-ethylpyridine, 2,4-dimethylpyridine, 2-methyl-4-hydroxypyridine, 2-hydroxy-4-methoxypyridine, 2- As the hydroxy-6-chloropyridine or the like, a cyclic nitrogen-containing compound such as phenanthroline, dipyridine or imidazole can also be used. These were prepared as a complex with copper as a catalyst and dissolved in the above glycol ether. Among them, pyridine, 2-hydroxypyridine, 2-methylpyridine, 1,10-phenanthroline and 2,2' dipyridine are preferably used.

As the alcohol used in the raw material of the present invention, various compounds having a hydroxyl group such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1- can be used. a saturated or unsaturated aliphatic alcohol having 1 to 20 carbon atoms such as octanol, 1-nonanol, 1-octadecyl alcohol, propenol, 2-buten-1-ol, 2-hexen-1-ol An alicyclic alcohol having 3 to 7 carbon atoms such as cyclohexanol or cyclopentanol; an aromatic alcohol such as benzyl alcohol or phenylethyl alcohol. Further, the alcohol to be used is not limited to a monohydric alcohol, and a glycol such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol or propylene glycol, or a polyhydric alcohol such as glycerin may be used, wherein the desired reaction product is obtained. It is preferred to use methanol and ethanol.

The carbon monoxide and oxygen used as the raw materials do not necessarily have to be high-purity gases, and may be gases diluted with inert gases such as nitrogen, argon or carbon dioxide. Particularly under the reaction conditions, in order to prevent oxygen explosion, it is preferred to dilute the oxygen with an inert gas, that is, air can be used instead of oxygen.

The carbonic acid diester synthesis process of the present invention is carried out by reacting an alcohol with carbon monoxide and oxygen in the above liquid catalyst.

R is an alcohol residue, X is a ligand, and n is the number of ligands bound to CuCl.

The liquid catalyst used in the present invention has a molar ratio of the cyclic nitrogen-containing compound to the copper compound of from 0.5 to 100, preferably from 0.5 to 50, more preferably from 1 to 10. When the value is less than 0.1, an insoluble copper compound is present, and a uniform catalyst system cannot be formed; when the value exceeds 100, precipitation of a copper compound when alcohol is present is disadvantageous.

The molar ratio of the glycol ether to the copper compound used is from 5 to 200, preferably from 1 to 100, more preferably from 3 to 50. When the value is less than 0.5, a uniform catalyst system cannot be formed; when the value exceeds 200, the liquid The decrease in the concentration of copper in the catalyst is not conducive to obtaining a good reaction rate, which is disadvantageous.

The molar ratio of the raw material alcohol to the copper compound used is from 10 to 700, preferably from 30 to 500, more preferably from 50 to 300. When the value is less than 10, a good reaction rate cannot be obtained. When the value exceeds 700, the liquid catalyst The decrease in copper concentration is also unfavorable for obtaining a good reaction rate, which is disadvantageous.

The process conditions for producing the carbonic acid diester of the present invention are as follows: the reaction temperature is 50-200 ° C, preferably 50-150 ° C, more preferably 80-140 ° C; the partial pressure of carbon monoxide (CO partial pressure) is 0.1-50 Kg / cm ² preferably 1-30Kg / cm2, more preferably 1-25Kg / cm ^2; oxygen partial pressure (O2 partial pressure) of 0.005-10Kg / cm ^2, preferably 0.005-5Kg / cm ^2, more preferably 0.01-3Kg /cm ² . When the reaction temperature is lower than 30 °C, a sufficient reaction rate is not obtained. On the other hand, the reaction temperature exceeds 200 °C, and by-products are increased to cause decomposition of unfavorable glycol ethers. Further, when the CO partial pressure is less than 0.1 kg/cm ² , a sufficient reaction rate cannot be obtained. On the other hand, when the CO partial pressure exceeds 50 kg/cm ² , the cost of the pressure-resistant container (reactor) increases, which is economically unsuitable. Further, when the partial pressure of O _{2 is} less than 0.001 kg/cm ² , a sufficient reaction rate is not obtained, and on the other hand, when the partial pressure of O ₂ exceeds 10 kg/cm ² , an adverse oxidative decomposition of glycol ether occurs.

The formation reaction of the carbonic acid diester of the present invention can be carried out in a batch type and in a continuous type, and can be carried out in any manner.

A liquid catalyst was added to the reactor to introduce CO and O ₂ into the reactor. As the form of the reactor, various conventionally known reactors having a stirring tank, a bubble column, and the like which can sufficiently contact the gas and liquid can be used. In this batch reaction, CO is added in an amount of from 8 to 200 mol/hr, preferably from 10 to 100 mol/hr, per mol of the copper compound; and O ₂ is added in an amount of from 0.08 to 4 mol/hr, preferably 0.1- 2 mol/hr.

The resulting carbonic acid diester is recovered from the reactor in the gas phase, and a supplementary amount of alcohol and pyridine and glycol ethers are added to the residual liquid for the second batch reaction.

The carbonic acid diester recovered as a liquid phase from the reactor can be distilled and recovered in a distillation column. At this time, the residual liquid in the distillation column (containing a copper catalyst, a cyclic nitrogen-containing compound, and a glycol ether) can be returned to the reactor, and a supplementary amount of an alcohol, a cyclic nitrogen-containing compound, and a glycol ether can be added to the reaction. In the apparatus, the second batch reaction was carried out. The liquid phase extraction method generally separates the product in the distillation column, which is more efficient than the gas phase extraction method.

In the carbonic acid diester formation process, the reactions are carried out separately in sequence. In this case, the liquid catalyst is first added to the reactor, the partial pressure of oxygen is controlled to 0.001-10 Kg/cm ² , after the reaction at 30-150 ° C, the oxygen is removed, and then the partial pressure of CO is controlled at 0.1-50 Kg. /cm ² , reacted at 30-180 ° C to obtain a carbonic acid diester.

To the reactor, alcohol, CO and O ₂ are continuously added, and if necessary, a supplementary amount of a cyclic nitrogen-containing compound or a glycol ether is added, and on the other hand, the product (carbonic acid diester) is continuously taken out by a recovery method. For the form of the reactor, various conventionally known reactors such as a stirred tank and a bubble column can be used, and the reaction product can be taken out by a gas phase extraction method or a liquid phase extraction method. In the latter case, it is usually used. The reaction product is separated from the distillation apparatus provided outside, and the residual liquid (copper-containing catalyst, cyclic nitrogen-containing compound, and glycol ether) in the distillation column is returned to the reactor. The liquid phase extraction method generally separates the product in the distillation column, which is more efficient than the gas phase extraction method.

In a continuous reaction, the two reactors are connected in series, and the oxidation process and the carbonylation process in each reactor are successively performed. The reaction conditions of CO partial pressure, O ₂ partial pressure, temperature and the like in each process are the same as those described above. Since the oxidation process and the carbonylation process are carried out separately, it is possible to avoid mixing of CO and O _{2 to} form an explosive mixture. So can form such a system. This is because the catalyst of the present invention is a stable homogeneous catalyst system.

After the reaction, the activity of the liquid catalyst of the present invention is lowered, and the catalyst having reduced activity is contacted with carbon monoxide to be regenerated. In order to regenerate the catalyst, the liquid catalyst having reduced activity is contacted with carbon monoxide, and the partial pressure of carbon monoxide is 0.1 kg/cm ² or more, preferably 0.5 kg/cm ² or more, and the upper limit of the partial pressure of carbon monoxide is not limited, but the maximum is 50 kg. When the CO partial pressure is less than 0.1 kg/cm ² , the liquid catalyst cannot be sufficiently regenerated, and when the CO partial pressure exceeds 50 kg/cm ² , it is disadvantageous to increase the price of the apparatus. The temperature at which the liquid catalyst is contacted with CO is 50 to 200 ° C, preferably 70 to 150 ° C. When the contact temperature is lower than 50 ° C, the liquid catalyst cannot be sufficiently regenerated, and when the contact temperature exceeds 200 ° C, decomposition of glycol ethers is disadvantageous.

The regenerated liquid catalyst thus obtained can be used as a liquid catalyst in a process for producing a carbonic acid diester, and when the liquid catalyst having reduced activity is regenerated, it is not necessary to regenerate all of the liquid catalyst, and a part thereof can be regenerated, and the partially regenerated liquid catalyst can be regenerated. A mixture with the unregenerated liquid catalyst is added to the reaction system.

The regeneration of the liquid catalyst can be carried out in a reactor for producing a carbonic acid diester, or can be carried out in a specially provided liquid catalyst regeneration device.

Detailed ways

Example

a liquid catalyst for use in the production of a carbonic acid diester by reacting an alcohol with carbon monoxide and oxygen in accordance with the present invention, which comprises

(1) Copper compound

(2) cyclic nitrogen-containing compounds and

(3) a glycol ether represented by the following formula (I),

R ¹ O[CH(R ² )CH ₂ O] _n R ³ (I)

Wherein R ¹ represents an alkyl group of ^{1 to} 8 carbon atoms, R ² represents an alkyl group of 1 to 3 carbon atoms or hydrogen, R ³ represents an alkyl group of 1 to 8 carbon atoms or hydrogen, and n represents 1-16. Integer,

A liquid catalyst comprising a solution of the above copper compound in a dissolved state is allowed to react with an alcohol, carbon monoxide and oxygen.

Wherein the cyclic nitrogen-containing compound is a substituted or unsubstituted pyridine compound.

Wherein, the molar ratio of the cyclic nitrogen-containing compound to the copper compound is in the range of 0.5 to 100.

Wherein, the molar ratio of the glycol ether to the copper compound is in the range of 5 to 200.

Preferably, the carbon monoxide is contacted with the liquid catalyst at a partial pressure of carbon monoxide of 50 to 200 ° C and 0.1 to 50 kg/cm ² .

More preferably, the partial pressure of oxygen during the reaction is in the range of from 0.010 to 10 kg/cm ² .

Specifically, the partial pressure of carbon monoxide at the time of the reaction is in the range of 0.1 to 50 kg/cm ² .

More specifically, the reaction temperature is 50 to 200 °C.

In any one of the foregoing liquid catalysts, a process for producing a carbonic acid diester of a reaction solution containing a carbonic acid diester by reacting an alcohol with carbon monoxide and oxygen; and a process for separating a carbonic acid diester of the carbonic acid diester from the reaction solution; A liquid catalyst regeneration process in which a liquid catalyst obtained by separating a carbonic acid diester is contacted with carbon monoxide.

The copper compound includes a copper halide, a mineral acid of copper, an organic acid salt of copper, a complex salt of copper, and the like, and the copper compound may be a monovalent copper (I) compound and/or a divalent copper (II) compound.

The above copper halides include chlorides, bromides and iodides, and specific examples are CuCl, CuCl ₂ , CuBr, CuBr ₂ , CuI and the like.

The above copper mineral acid salt includes a nitrate, a carbonate, a borate, a phosphate, etc., and specific examples thereof include Cu(NO ₃ ) ₂ , CuCO ₃ ·Cu(OH) ₂ ·H ₂ O, CuB ₄ O _{7 .} , CuPO _4, etc.

The copper organic acid salt includes a carboxylate, a sulfonate, a phosphate, a phosphonate, and the like, and specific examples thereof include a formate, an acetate, an oxalate, and the like.

The copper complex salt may be a copper complex salt such as a chain amine such as trimethylamine or a cyclic amine such as pyridine or an organic phosphine compound such as triphenylphosphine as a ligand.

The copper compound used in the present invention is particularly preferably cuprous chloride (CuCl) or a complex thereof from the viewpoints of catalyst activity and selectivity to carbonic acid diester.

In the glycol ether compound represented by the formula (I) used in the invention, R ¹ is an alkyl group of ¹ to 8 carbon atoms, preferably 1 to 4 carbon atoms, more preferably 1 to 2 carbon atoms; R ² is an alkyl group of 1 to 4 carbon atoms or hydrogen, preferably hydrogen or methyl, more preferably hydrogen; R ³ is 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, more preferably 1 An alkyl group of 2 carbon atoms or hydrogen; n is an integer from 1 to 16, preferably from 1 to 6, more preferably from 2 to 4. When the number of carbon atoms of R ¹ exceeds 6, the solubility of the copper compound may decrease. When the number of carbon atoms of R ² exceeds 2, the solubility of the copper compound may decrease, and when the number of carbon atoms of R ³ exceeds 6, There is still a case where the solubility of the copper compound is lowered; in addition, when n exceeds 12, there is a disadvantage that the solubility of the copper compound is lowered and the viscosity of the cuprous catalyst is increased.

The glycol ether used in the present invention is a compound represented by the above formula (I), and a typical glycol ether is 1 mole of methanol, ethanol, propanol and/or butanol and 2 to 12 moles of ethylene oxide and/or a ring. a glycerol monoalkyl ether compound formed by oxypropane; another typical glycol ether compound is substituted with a lower alkyl group such as methyl, ethyl, propyl or butyl to the above-mentioned glycerol monoalkyl ether terminal OH A glycol dialkyl ether compound obtained by H. Further, the above glycol ether compounds may be used singly or in the form of a mixture of two or more.

Such a glycol ether compound has high solubility in CO and oxygen, and high solubility in a complex of copper and a cyclic nitrogen-containing compound, so that precipitation of a copper compound can be avoided. Such glycol ether compounds are easily synthesized by etherification of glycols and alcohols, and are also commercially available. Glycol ether is widely used as a gas absorbent. It has excellent solubility in various gaseous substances, stable chemical properties, no corrosiveness, no formation of insolubles and precipitates, high thermal stability, and poor solvent properties. Low pressure, low solvent loss and other characteristics.

The cyclic nitrogen-containing compound used in the present invention is pyridine or a pyridine compound having a substituent such as an alkyl group, an alkoxy group or a halogen atom which does not impair the reaction of a carbonic acid diester on the pyridine ring, and examples thereof include pyridine. , 2-hydroxypyridine, 2-methylpyridine, 2-ethylpyridine, 2,4-dimethylpyridine, 2-methyl-4-hydroxypyridine, 2-hydroxy-4-methoxypyridine, 2- As the hydroxy-6-chloropyridine or the like, a cyclic nitrogen-containing compound such as phenanthroline, dipyridine or imidazole can also be used. These were prepared as a complex with copper as a catalyst and dissolved in the above glycol ether. Among them, pyridine, 2-hydroxypyridine, and 2- are preferably used. Methylpyridine, 1,10-phenanthroline and 2,2' dipyridine.

As the alcohol used in the raw material of the present invention, various compounds having a hydroxyl group such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1- can be used. a saturated or unsaturated aliphatic alcohol having 1 to 20 carbon atoms such as octanol, 1-nonanol, 1-octadecyl alcohol, propenol, 2-buten-1-ol, 2-hexen-1-ol An alicyclic alcohol having 3 to 7 carbon atoms such as cyclohexanol or cyclopentanol; an aromatic alcohol such as benzyl alcohol or phenylethyl alcohol. Further, the alcohol to be used is not limited to a monohydric alcohol, and a glycol such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol or propylene glycol, or a polyhydric alcohol such as glycerin may be used, wherein the desired reaction product is obtained. It is preferred to use methanol and ethanol.

The carbon monoxide and oxygen used as the raw materials do not necessarily have to be high-purity gases, and may be gases diluted with inert gases such as nitrogen, argon or carbon dioxide. Particularly under the reaction conditions, in order to prevent oxygen explosion, it is preferred to dilute the oxygen with an inert gas, that is, air can be used instead of oxygen.

The carbonic acid diester synthesis process of the present invention is carried out by reacting an alcohol with carbon monoxide and oxygen in the above liquid catalyst.

R is an alcohol residue, X is a ligand, and n is the number of ligands bound to CuCl.

The liquid catalyst used in the present invention has a molar ratio of the cyclic nitrogen-containing compound to the copper compound of from 0.5 to 100, preferably from 0.5 to 50, more preferably from 1 to 10. When the value is less than 0.1, an insoluble copper compound is present, and a uniform catalyst system cannot be formed; when the value exceeds 100, precipitation of a copper compound when alcohol is present is disadvantageous.

The molar ratio of the glycol ether to the copper compound used is from 5 to 200, preferably from 1 to 100, more preferably from 3 to 50. When the value is less than 0.5, a uniform catalyst system cannot be formed; when the value exceeds 200, the liquid The decrease in the concentration of copper in the catalyst is not conducive to obtaining a good reaction rate, which is disadvantageous.

The molar ratio of the raw material alcohol to the copper compound used is from 10 to 700, preferably from 30 to 500. More preferably, it is in the range of 50-300. When the value is less than 10, a better reaction rate cannot be obtained. When the value exceeds 700, the concentration of copper in the liquid catalyst is lowered, which is not conducive to obtaining a good reaction rate, which is disadvantageous. .

The process conditions for producing the carbonic acid diester of the present invention are as follows: the reaction temperature is 50-200 ° C, preferably 50-150 ° C, more preferably 80-140 ° C; the partial pressure of carbon monoxide (CO partial pressure) is 0.1-50 Kg / cm ² preferably 1-30Kg / cm ^2, more preferably 1-25Kg / cm ^2; partial pressure of oxygen (O ₂ partial pressure) of 0.005-10Kg / cm ^2, preferably 0.005-5Kg / cm ^2, more preferably 0.01 -3Kg/cm ² . When the reaction temperature is lower than 30 ° C, a sufficient reaction rate is not obtained, and on the other hand, the reaction temperature exceeds 200 ° C, and by-products are increased to cause decomposition of unfavorable glycol ethers. Further, when the CO partial pressure is less than 0.1 kg/cm ² , a sufficient reaction rate cannot be obtained. On the other hand, when the CO partial pressure exceeds 50 kg/cm ² , the cost of the pressure-resistant container (reactor) increases, which is economically unsuitable. Further, when the partial pressure of O _{2 is} less than 0.001 kg/cm ² , a sufficient reaction rate is not obtained, and on the other hand, when the partial pressure of O ₂ exceeds 10 kg/cm ² , an adverse oxidative decomposition of glycol ether occurs.

The formation reaction of the carbonic acid diester of the present invention can be carried out in a batch type and in a continuous type, and can be carried out in any manner.

A liquid catalyst was added to the reactor to introduce CO and O ₂ into the reactor. As the form of the reactor, various conventionally known reactors having a stirring tank, a bubble column, and the like which can sufficiently contact the gas and liquid can be used. In this batch reaction, CO is added in an amount of from 8 to 200 mol/hr, preferably from 10 to 100 mol/hr, per mol of the copper compound; and O ₂ is added in an amount of from 0.08 to 4 mol/hr, preferably 0.1- 2 mol/hr.

The resulting carbonic acid diester is recovered from the reactor in the gas phase, and a supplementary amount of alcohol and pyridine and glycol ethers are added to the residual liquid for the second batch reaction.

The carbonic acid diester recovered as a liquid phase from the reactor can be distilled and recovered in a distillation column. At this point, the residual liquid in the distillation column (containing copper catalyst, cyclic nitrogen) The compound and the glycol ether are returned to the reactor, and a supplementary amount of the alcohol, the cyclic nitrogen-containing compound and the glycol ether are added to the reactor to carry out the second batch reaction. The liquid phase extraction method generally separates the product in the distillation column, which is more efficient than the gas phase extraction method.

In the carbonic acid diester formation process, the reactions are carried out separately in sequence. In this case, the liquid catalyst is first added to the reactor, the partial pressure of oxygen is controlled to 0.001-10 Kg/cm ² , after the reaction at 30-150 ° C, the oxygen is removed, and then the partial pressure of CO is controlled at 0.1-50 Kg. /cm ² , reacted at 30-180 ° C to obtain a carbonic acid diester.

To the reactor, alcohol, CO and O ₂ are continuously added, and if necessary, a supplementary amount of a cyclic nitrogen-containing compound or a glycol ether is added, and on the other hand, the product (carbonic acid diester) is continuously taken out by a recovery method. For the form of the reactor, various conventionally known reactors such as a stirred tank and a bubble column can be used, and the reaction product can be taken out by a gas phase extraction method or a liquid phase extraction method. In the latter case, it is usually used. The reaction product is separated from the distillation apparatus provided outside, and the residual liquid (copper-containing catalyst, cyclic nitrogen-containing compound, and glycol ether) in the distillation column is returned to the reactor. The liquid phase extraction method generally separates the product in the distillation column, which is more efficient than the gas phase extraction method.

In a continuous reaction, the two reactors are connected in series, and the oxidation process and the carbonylation process in each reactor are successively performed. The reaction conditions of CO partial pressure, O2 partial pressure, temperature and the like in each process are the same as those described above. Since the oxidation process and the carbonylation process are carried out separately, it is possible to avoid mixing of CO and O2 to form an explosive mixture. So can form such a system. This is because the catalyst of the present invention is a stable homogeneous catalyst system.

After the reaction, the activity of the liquid catalyst of the present invention is lowered, and the catalyst having reduced activity is contacted with carbon monoxide to be regenerated. In order to regenerate the catalyst, the liquid catalyst having reduced activity is contacted with carbon monoxide, and the partial pressure of carbon monoxide is 0.1 kg/cm ² or more, preferably 0.5 kg/cm ² or more, and the upper limit of the partial pressure of carbon monoxide is not limited, but the maximum is 50 kg. / cm ^2; CO partial pressure 0.1kg / ² when cm, the liquid can not sufficiently regenerated catalyst, CO partial pressure of more than 50kg / ² when cm, so that an increase in the price of the device is disadvantageous. The temperature at which the liquid catalyst is contacted with CO is 50 to 200 ° C, preferably 70 to 150 ° C. When the contact temperature is lower than 50 ° C, the liquid catalyst cannot be sufficiently regenerated, and when the contact temperature exceeds 200 ° C, decomposition of glycol ethers is disadvantageous.

The regenerated liquid catalyst thus obtained can be used as a liquid catalyst in a process for producing a carbonic acid diester, and when the liquid catalyst having reduced activity is regenerated, it is not necessary to regenerate all of the liquid catalyst, and a part thereof can be regenerated, and the partially regenerated liquid catalyst can be regenerated. A mixture with the unregenerated liquid catalyst is added to the reaction system.

The regeneration of the liquid catalyst can be carried out in a reactor for producing a carbonic acid diester, or can be carried out in a specially provided liquid catalyst regeneration device.

The liquid catalyst of the present invention can selectively promote the formation reaction of carbonic acid diester, and even if the liquid catalyst contains an alcohol, the copper compound does not precipitate, and the reaction system exists in a uniform solution. Therefore, since the liquid catalyst of the present invention is used, the carbonic acid diester can be produced with good selectivity and high yield, and the carbonic acid diester can be easily recovered from the obtained reaction product. Since the reaction product obtained by the liquid catalyst of the present invention is a homogeneous solution containing no solid matter, it is possible to directly carry out distillation, and it is possible to easily obtain a high-purity carbonic acid diester.

Further, the liquid catalyst of the present invention is much less corrosive than the methanol/CuCl mixture currently used as a liquid catalyst, and the liquid catalyst of the present invention is easily regenerated, and the catalyst having reduced activity can be regenerated by contact with CO.

Claims (9)

1. A method for producing a carbonic acid diester, characterized in that the method comprises a liquid catalyst used in the reaction of an alcohol with carbon monoxide and oxygen to produce a carbonic acid diester, which comprises

   (1) Copper compound

   (2) cyclic nitrogen-containing compounds and

   (3) a glycol ether represented by the following formula (I),

   R ¹ O[CH(R ² )CH ² O] _n R ³ (I)

   Wherein R ¹ represents an alkyl group of ^{1 to} 8 carbon atoms, R ² represents an alkyl group of 1 to 3 carbon atoms or hydrogen, R ³ represents an alkyl group of 1 to 8 carbon atoms or hydrogen, and n represents 1-16. Integer,

   A liquid catalyst comprising a solution of the above copper compound in a dissolved state is allowed to react with an alcohol, carbon monoxide and oxygen.
2. The method for producing a carbonic acid diester according to claim 1, wherein the cyclic nitrogen-containing compound is a substituted or unsubstituted pyridine compound.
3. The method for producing a carbonic acid diester according to claim 1 or 2, wherein a molar ratio of the cyclic nitrogen-containing compound to the copper compound is in the range of 0.5 to 100.
4. The method for producing a carbonic acid diester according to claim 1 or 2, wherein the molar ratio of the glycol ether to the copper compound is in the range of 5 to 200.
5. The method for producing a carbonic acid diester according to claim 1, wherein the carbon monoxide is contacted with the liquid catalyst at a partial pressure of carbon monoxide of 50 to 200 ° C and 0.1 to 50 kg / cm ² .
6. The method of producing a carbonic diester according to claim 1, characterized in that the oxygen partial pressure during the reaction is in the range 0.010-10kg / cm ^2.
7. The method for producing a carbonic acid diester according to claim 6, wherein the partial pressure of carbon monoxide during the reaction is in the range of 0.1 to 50 kg/cm ² .
8. The method for producing a carbonic acid diester according to claim 1 or 7, wherein the reaction temperature is 50 to 200 °C.
9. The method for producing a carbonic acid diester according to any one of claims 1 to 7, wherein in the liquid catalyst according to any one of claims 1 to 2, the alcohol and carbon monoxide and oxygen are reacted to obtain a diester-containing product. a process for producing a carbonic acid diester of the reaction solution; a process for separating a carbonic acid diester of the carbonic acid diester from the reaction solution; and a liquid catalyst regeneration process for contacting the liquid catalyst obtained by separating the carbonic acid diester with carbon monoxide.