JPH05320099A - Production of carbonic acid ester - Google Patents

Abstract

PURPOSE:To provide a production method capable of preventing deposition of metals of platinum group and industrially and efficiently producing a carbonic acid ester by continuous reaction while stably keeping high catalytic activity. CONSTITUTION:An alcohol is made to react with carbon monoxide and oxygen in the presence of a catalyst in a liquid phase to produce a carbonic acid ester. The catalyst is composed of a platinum group compound, a weak acid salt or halide of copper and a weak acid salt or halide of an alkaline earth metal. The reaction is carried out under a condition where a residence time of a liquid in a reactor is <=60min. Concretely, this reaction is carried out at 100-140 deg.C and the alcohol containing a catalyst is made to react with a raw material gas while continuously feeding these raw materials and the reaction liquid and gas from the reaction system are continuously taken out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a carbonic acid ester useful as a polymer raw material, an intermediate for pharmaceuticals and agricultural chemicals, a solvent and the like.

[0002]

2. Description of the Related Art As a method for producing a carbonic acid ester, a method of reacting an alcohol with phosgene is industrially adopted. However, this method requires the use of highly toxic phosgene, and a large amount of strongly corrosive hydrochloric acid is by-produced due to the reaction between alcohol and phosgene.

Therefore, there has been proposed a method for producing a carbonic acid ester by reacting alcohol, carbon monoxide and oxygen in the presence of a catalyst without using phosgene. The catalyst is roughly classified into a copper-based catalyst containing a copper compound as a main catalyst and a palladium-based catalyst containing a palladium compound as a main catalyst.

Copper-based catalysts are disclosed in JP-B-45-11129 and JP-B-60-58739.
However, the activity of the copper-based catalyst is relatively low. Therefore, in order to obtain a practical reaction rate, the catalyst is used at a high concentration of several mol / L (several tens% in terms of weight%), and the carbon monoxide partial pressure is as high as 10 kg / cm ² or more. Need to react. In addition, since the oxidizing divalent copper ion that is a catalytically active species is present at a high concentration, the corrosion of the reactor and the like is significant, and a large amount of insoluble monovalent copper compound generated by recycling the catalyst exists as a slurry. For the reactor,
There is a large amount of wear damage to the valve. Therefore, it is not industrially satisfactory from the viewpoint of stable operation of the high-pressure reaction.

On the other hand, regarding the reaction using a palladium-based catalyst, Japanese Examined Patent Publication No. 61-8816 and Japanese Examined Patent Publication No. 61-43.
No. 338 is disclosed. In this method, a palladium compound is used as a main catalyst and a copper oxide and an alkali metal compound are used in combination. Palladium compounds offer various advantages due to their higher activity compared to copper catalyst systems. That is, it is possible to obtain a sufficient reaction rate even when the amount of the palladium catalyst is as small as about 1/1000 as compared with the copper-based catalyst, and the copper used in combination for reoxidizing the palladium is used. Alternatively, the amount of ions such as iron can be reduced to about 1/10 to 1/100 as compared with the copper-based catalyst.
Further, since the palladium-based catalyst has higher activity than the copper-based catalyst, a sufficient reaction rate can be obtained even under the condition of low carbon monoxide partial pressure.

However, the palladium catalyst is relatively unstable and, in the presence of alcohol, is rapidly reduced to palladium metal under high temperature conditions. Therefore, not only slurry is generated, but also the inner wall of the reactor may be plated. Further, in the case of industrially producing a carbonate ester, in order to obtain an economically advantageous reaction rate, 100 ° C.
It is necessary to react at the above temperature. Further, at such a reaction temperature, the vapor pressure of the liquid component increases,
Carbon monoxide and oxygen, as well as the inert components used to prevent the formation of explosive mixtures, are gaseous. Therefore, in order to allow carbon monoxide, oxygen, and an inert gas, which are raw material gases, to exist in the reaction system together with the liquid component, the reaction is carried out under pressure.

In such a reaction system, the amount of the palladium metal slurry is smaller than that of the copper catalyst, but it is not easy to extract the slurry from the high pressure reactor. Further, when the slurry is extracted from the high-pressure reactor, stable operation cannot be performed, which is an important problem in industrially producing carbonate ester. In addition, when slurry is deposited or adhered to the inside of the reactor or pipes, when the catalyst is circulated and reused, the amount of palladium in the catalyst component decreases and the reaction becomes unstable and expensive. The amount of palladium metal used increases, and the manufacturing cost rises.

In order to solve such a problem, it is considered that activated carbon is allowed to coexist in the reaction system, the produced palladium metal is adsorbed on the activated carbon and taken out from the reactor. But,
In order to completely adsorb the palladium metal, 10 to 50 times by weight of activated carbon is needed with respect to the palladium metal. And it is not easy industrially to extract a large amount of activated carbon from the high-pressure reactor.

It is also possible to adopt a batch reaction and take out the solids in the reactor after completion of the reaction. However, in the batch reaction, not only the temperature and pressure change frequently but also the reaction time However, it is not suitable for mass production because it requires long heating, cooling and liquid transfer operations. For mass production, a continuous reaction system in which the raw materials are continuously supplied to the reactor and the reaction liquid is continuously withdrawn is advantageous. However, it is difficult to adopt the continuous reaction because the palladium metal is deposited as described above.

[0010]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method capable of preventing the precipitation of platinum group metals and stably producing a carbonic acid ester while stably maintaining a high catalytic activity. ..

Another object of the present invention is to provide a method capable of smoothly carrying out a continuous reaction and industrially efficiently producing a carbonate ester.

[0012]

As a result of intensive studies, the present inventors have found that the reaction of a specific residence time can prevent precipitation of a platinum group metal without lowering the production rate of carbonic acid ester. completed.

That is, the present invention is a method for producing a carbonic acid ester by reacting an alcohol, carbon monoxide and oxygen in a liquid phase, which comprises a platinum group compound, a weak acid salt or halide of copper, and an alkaline earth metal. There is provided a method for producing a carbonic acid ester, which comprises reacting a liquid in a reactor in the presence of a catalyst comprising a weak acid salt or a halide under the condition that the residence time of the liquid is 60 minutes or less.

The above reaction is preferably carried out at a reaction temperature of 100 to 140 ° C., the alcohol containing the catalyst and the raw material gas are continuously fed to react, and the reaction liquid and the gas are continuously taken out from the reaction system. Is preferred.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings as needed.

The alcohol includes compounds having one or more hydroxyl groups in the molecule, for example, monohydric or polyhydric aliphatic, alicyclic and aromatic alcohols. The aromatic alcohol is used to include phenols having a phenolic hydroxyl group.

As the monohydric alcohol, for example, methanol, ethanol, propanol, isopropanol,
Butanol, isobutanol, t-butanol, pentanol, hexanol, heptanol, octanol,
Saturated aliphatic alcohols such as 2-ethylhexanol;
Unsaturated aliphatic alcohols such as allyl alcohol, crotonyl alcohol, and propargyl alcohol are exemplified.

As the polyhydric alcohol, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol,
Polypropylene glycol, trimethylene glycol,
Examples include tetramethylene glycol, hexamethylene glycol, neopentyl glycol, glycerol, pentaerythritol and the like.

Alicyclic alcohols include, for example, cyclohexanol and methylcyclohexanol.

Examples of aromatic alcohols include monovalent aromatic alcohols such as phenol, α-naphthol, β-naphthol, and benzyl alcohol; polyvalent aromatic alcohols such as catechol, resorcinol, hydroquinone, and pyrogallol. ..

The preferred alcohol is a monovalent saturated or unsaturated alcohol having a high reaction rate, for example, having 1 to 1 carbon atoms.
6, preferably an alcohol having about 1 to 4 carbon atoms.
Particularly preferred alcohols include methanol, ethanol and the like.

As the catalyst component constituting the catalyst, a compound which is soluble in the reaction solution, particularly alcohol, is used under the reaction conditions.

The platinum group element of the platinum group compound is, for example,
Includes ruthenium, rhodium, palladium, osmium, iridium and platinum. Examples of the platinum group compound include halides such as fluorine, chlorine, bromine and iodine; acetic acid, propionic acid, trifluoroacetic acid, formic acid, citric acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, p-toluene. Organic acid salts such as sulfonic acid; inorganic acid salts such as sulfuric acid, hydrochloric acid and nitric acid.

Preferred platinum group compounds are halides of ruthenium, rhodium and palladium, especially chlorides. Particularly preferred platinum group compounds include palladium chloride and the like.

The platinum group compounds may be used alone or in combination of two or more. The platinum group compound may be used in any concentration as long as it can be dissolved in alcohol. When the platinum group compound is used in an amount smaller than that of the copper compound, the platinum group compound can be oxidized by the copper compound which is present in a larger amount than the platinum group compound, which is advantageous in conducting a continuous catalytic reaction. Further, the copper compound has a function of promoting dissolution of the platinum group compound in the reaction solution. Therefore, with respect to the weak acid salt and / or halide of copper, 0.05 mol or less, preferably 0.001 to
It is about 0.05 mol.

A divalent copper compound is used as the copper compound. Weak copper salts include acetic acid, propionic acid, pivalic acid, trichloroacetic acid, trifluoroacetic acid, methanesulfonic acid, trifluoromethanesulfonic acid, formic acid, lactic acid, citric acid, benzoic acid, benzenesulfonic acid, p-toluenesulfonic acid. Organic acid salts such as; inorganic acid salts such as hydrobromic acid, boric acid, carbonic acid; phenol, cresol, p
-Salts with phenols such as chlorophenol and the like can be mentioned. Copper halides include, for example, fluorinated second
Copper, cupric chloride, cupric bromide and the like are included.

Of these copper compounds, organic acid salts such as acetate and halides such as cupric chloride are frequently used.

As the weak acid salt of copper and the halide, one kind or two kinds or more of the same kind or different kinds of compounds may be used.

The amount of the weak acid salt and / or halide of copper used can be selected within a wide range, and for example, 1 to 3000 mmol, preferably 10 to 100, per 1 L of alcohol.
It is 0 mmol, more preferably about 10 to 500 mmol.

The alkaline earth metals include calcium, magnesium, strontium, barium and the like.
Weak acid salts of alkaline earth metals include acetic acid, propionic acid, pivalic acid, trichloroacetic acid, trifluoroacetic acid,
Organic acid salts such as lactic acid, citric acid, oxalic acid, benzoic acid and p-toluenesulfonic acid; inorganic acid salts such as hydrobromic acid, boric acid and carbonic acid. In addition, the alkaline earth metal halides include, for example, fluorides, chlorides, bromides, and iodides.

Of these alkaline earth metal compounds,
Organic acid salts such as acetate and chloride are often used.

The alkaline earth metal compound is the pH of the reaction solution.
The effect of increasing carbon dioxide and suppressing the conversion reaction of carbon monoxide to carbon dioxide and increasing the selectivity of carbonate ester. The amount of the alkaline earth metal compound used is, for example, about 0.1 to 10 times mol, preferably about 1 to 5 times mol, of the copper compound.

At least one of the platinum group compound, the copper compound and the alkali metal compound is
It preferably contains a halogen atom, especially a chlorine atom. In particular, the copper compound preferably contains cupric chloride.

In the catalyst system, the atomic ratio of halogen to copper (halogen / copper ratio) is, for example, about 0.5 to 2, preferably about 1.5 to 1.8. The halogen / copper ratio is
If it is less than 0.5, the solubility of copper is reduced, and if it exceeds 2, the reaction rate is significantly reduced.

The main feature of the present invention is that by controlling the residence time of the liquid in the reactor, it is possible to prevent the solidification and precipitation of the metal, which is a problem in the platinum group catalyst. for that reason,
According to the method of the present invention, a platinum-based catalyst can be taken out from a high-pressure reactor in a dissolved state while maintaining high catalytic activity even at high pressure, and a carbonate ester can be produced stably and industrially.

In the method of the present invention, the reaction is carried out under the condition that the residence time of the liquid in the reactor is 60 minutes or less, preferably 5 to 50 minutes, more preferably 15 to 45 minutes.

The residence time of the liquid can be grasped as the residence time of the liquid at the reaction temperature,
A high correlation is recognized between the residence time T of the liquid represented by the following formula and the precipitation of the platinum group metal.

Residence time T (minutes) = [(V1 × ρ1 / ρ2
) / V2] where V1 is the volume of the reaction solution and V2 is 20 ° C.
Shows the volume of the feed liquid per unit time, ρ1 shows the density of alcohol at the reaction temperature, and ρ2 shows the density of alcohol at 20 ° C.

The residence time T is converted into a liquid volume of 20 ° C., since the liquid volume in the reactor during steady operation is converted to a liquid volume of 20 ° C. because the density of the charged alcohol changes with temperature.
It is a value that is divided by the volume of the charged liquid per unit time at 0 ° C.

The residence time T can be easily controlled by adjusting the supply amount, withdrawal amount, and reaction temperature of the liquid component to the reactor.

The reason why the precipitation of platinum group metal can be prevented by controlling the residence time is presumed to be as follows.

That is, in the production of the carbonate ester, water is produced together with the carbonate ester as the reaction proceeds. It is known that this water typically reacts with copper compounds, such as copper halides, to form solid hydroxyhalogen halides. According to the experience of the present inventors, when the reaction solution is left for a long time, the by-produced water reacts with the copper compound of the cocatalyst to produce an insoluble solid substance which is considered to be a copper hydroxyhalide.

The present inventors have investigated the function of copper hydroxyhalide. As a result, the initial particulate copper hydroxyhalide produced by the reaction of water and a copper compound is used as a cocatalyst that is active again during the reaction. Although it works, it was found that when the generated fine particles were exposed to a high temperature for a long time, a crystal grew and grew into an inactive copper hydroxyhalide called atacamaite and the cocatalyst activity was lowered. The degree of this crystal growth is greater as the temperature is higher and the time is longer. Therefore, when the residence time of the liquid is lengthened, the originally active fine particles of copper hydroxyhalide aggregate and crystallize. Therefore, it is presumed that the ability of the copper compound to oxidize the platinum group compound is lowered, and thus the solubility of the platinum group compound is lowered.

The reaction temperature can be selected within a range that does not impair the reaction rate and can suppress the precipitation and solidification of the platinum group metal, and is, for example, 50 to 200 ° C, preferably 100 to 150 ° C, more preferably 100 to 140 ° C. It is a degree. A particularly preferable reaction temperature is about 100 to 135 ° C.

The reaction temperature affects the solubility of the platinum group compound in relation to the residence time. If the reaction temperature is too high, the reduction reaction of the platinum group compound with alcohol tends to proceed preferentially, and Reduces the solubility of group compounds,
If the reaction temperature is too low, the reaction temperature will decrease. Although the reaction proceeds even at a temperature of 100 ° C. or lower, the reaction rate tends to be low and the oxalate ester by-product rate tends to increase. Further, in the case of shortening the residence time of the liquid in the reactor, it is possible to react at a high temperature, but the platinum group metal is likely to precipitate, the vapor pressure of the reaction liquid increases, the overall pressure Since the temperature rises, it becomes necessary to use a reactor having a high pressure resistance, which is not preferable in terms of equipment cost and economy.

The carbon monoxide partial pressure in the feed gas can be selected within a range that does not reduce the reaction rate. When the carbon monoxide partial pressure increases, the amount of carbonic acid ester produced decreases and the amount of oxalate ester by-product tends to increase, and the by-produced oxalic acid reacts with the alkaline earth metal compound. ,
Precipitates as an insoluble salt. Therefore, the carbon monoxide partial pressure is usually 0.05 to 10 kg / cm ² , preferably 0.05 to 6.0 kg / cm ² , and more preferably 0.
It is about 5 to 5.0 kg / cm ² .

The oxygen partial pressure is not particularly limited because it does not affect the by-product of oxalate ester, but is usually a concentration at which an explosive mixture is not formed. The oxygen partial pressure can be appropriately selected within a wide range, for example, 0.05 to 10 kg / cm ² , preferably 0.05 to 5 kg / cm ² .

The reaction is usually carried out under high pressure. The pressure of the reaction system can be selected within a range that does not impair the reaction efficiency and can suppress the production of by-products, and for example, 5 to 50 kg / cm ² ,
It is preferably 10 to 30 kg / cm ² , and more preferably 15 to 25 kg / cm ² .

In the reaction, the catalyst may be added to the reaction system, but it is usually supplied to the reaction system together with the alcohol. In the preferred reaction, the catalyst is usually supplied to the reaction system as an alcohol solution.

Carbon monoxide and oxygen need not be high-purity gases, and may be diluted with a reaction-inert gas such as nitrogen, helium, argon or carbon dioxide.
The source gas is preferably diluted with an inert gas to prevent the formation of an explosive mixture. In that case, air may be used instead of oxygen, and nitrogen in the air may be used as an inert gas.

Carbon dioxide produced as a by-product of the reaction may be used as an inert gas for dilution. In a preferred method, unreacted carbon monoxide discharged from the reaction system is recycled to the reaction system together with carbon dioxide produced as a by-product. In this case, in the continuous reaction, the concentration of carbon dioxide in the circulating gas becomes high, so the loss of unreacted carbon monoxide that accompanies the emission of carbon dioxide can be minimized, and carbon monoxide can be effectively used. It is possible and economically more preferable.

The present invention is preferably applied to a continuous reaction system in which an alcohol containing a catalyst and a raw material gas are continuously fed and reacted to continuously take out a reaction liquid from a reaction system.
Particularly preferably, it is suitably applied to a continuous reaction system in which a reaction solution and a gas are continuously withdrawn from the reaction system.

The number of reaction vessels in the continuous reaction system is not particularly limited and may be either a parallel reaction system or a series reaction system. In particular, when the in-line reaction system is adopted, the reaction efficiency can be improved because it approaches the batch reaction, but the reaction may be continuously performed in a single reaction tank.

The reaction solution is subjected to a conventional separation process such as distillation or solvent extraction to produce a carbonate ester. According to the present invention, the precipitation of the platinum group metal can be significantly suppressed, so that the unreacted alcohol in the reaction liquid extracted from the reaction system can be recycled to the reaction system together with the catalyst.

FIG. 1 is a schematic diagram for explaining an example of a continuous reaction, and in this example, a reaction apparatus used in Examples described later is shown.

The reaction tank 1 has a first supply line 2 for supplying alcohol by a metering pump, a second supply line 3 for supplying carbon monoxide, and a first supply line 3 for supplying oxygen. The third supply line 4 and the fourth supply line 5 for supplying the inert gas are connected.

The alcohol containing the catalyst system having a predetermined concentration may be continuously supplied to the reaction tank 1 from the first supply line 2. Further, the third to fifth supply lines merge at their midpoints and extend into the liquid phase in the reaction tank 1. The flow rates of carbon monoxide, oxygen and the inert gas are controlled by valves.
The reactive gas component and the inert gas are usually sparged in the liquid phase at a predetermined composition ratio in order to enhance the gas-liquid contact efficiency.

The reaction tank 1 is equipped with a stirrer 6.
In this example, a plurality of disk turbine blades are used to efficiently perform the gas-liquid contact reaction.

Further, the reaction tank 1 is connected to a reaction liquid extraction line 7 communicating with the liquid phase, and a liquid for adjusting the liquid amount of the reaction liquid by continuously extracting the reaction liquid is connected to this line. A surface adjustment valve 8 is attached.

Further, an offgas line 10 equipped with a condenser 9 is connected to the reaction tank 1, and the offgas line 1
0 is a pressure control valve 1 for controlling the pressure of the reaction system
1 is attached. The gas component not condensed by the condenser 9 is guided to the outside of the reaction system through the pressure control valve 11, and the component condensed by the condenser 9 is circulated in the reaction tank 1 through the recycle line 12.

[0061]

EFFECTS OF THE INVENTION According to the method of the present invention, since the reaction is carried out for a specific residence time, the precipitation of platinum group metals can be prevented and the carbonate ester can be efficiently produced while maintaining a high catalytic activity stably.

Further, since the precipitation of the alkaline earth metal salt can be prevented, the carbonate ester can be industrially efficiently produced by the continuous reaction.

[0063]

EXAMPLES The present invention will be described in more detail based on the following examples.

Example 1 A glass-lined pressure resistant reactor (internal volume: 6 L) equipped with a magnetic stirrer was charged with palladium chloride (0.1%).
72 mmol / L, cupric chloride 50.3 mmol / L,
Copper acetate 6.7 mmol / L and magnesium acetate 57
A methanol solution in which mmol / L was dissolved was 5.2 L / h.
under a condition of r, carbon monoxide of 496 NL /
hr, oxygen 357 NL / hr and carbon dioxide 27
40 NL / hr was supplied from a spasher at the bottom of the reactor and reacted.

The temperature during the reaction was controlled at 110 ° C. by flowing a heat medium through the jacket provided in the reactor.
In addition, from the liquid level control valve provided at the bottom of the reactor,
The reaction liquid was continuously withdrawn to carry out the reaction while maintaining the liquid surface in the reactor at a liquid volume of 3 L.

Since the density of methanol at 110 ° C. is 0.700 g / cc and the density of methanol at 20 ° C. is 0.793 g / cc, the liquid amount in the reactor at 20 ° C. is 3 × 0.700 / 0.793 = 2.65
The liquid retention time T was 31 minutes.

Exhaust gas from the reactor was supplied to a condenser under pressure to remove condensed components consisting of methanol, dimethyl carbonate and water, and then the reaction pressure was 21 kg / cm ² G
It was discharged from the pressure control valve while being kept at. The methanol, dimethyl carbonate and water condensed by the condenser were returned to the reactor by a natural flow method through a U-shaped liquid seal tube. The temperature of the gas passed through the condenser is 20 ° C.
The temperature and flow rate of the cooling water were adjusted so as to be as follows.

During the reaction, in order to prevent the formation of an explosive mixture, the amount of oxygen in the supply gas is adjusted so that the oxygen concentration in the offgas is 4.5% at the start of the reaction and at the time of steady operation. Controlled.

Dimethyl carbonate in the reaction liquid extracted from the reactor was quantified by an internal standard gas chromatography method, and the amount of palladium was quantified by atomic absorption spectrometry.

When the reaction was carried out under such conditions, the reaction liquid extracted from the reactor was a green transparent liquid, and a solid substance believed to be palladium black could not be visually confirmed. The production rate of dimethyl carbonate based on the 3 L reaction solution was 2.95 mol / L / hr. Also, the concentration of palladium dissolved in the reaction solution is 91 p.
pm and 100 of the palladium component charged to the reaction system
% Was dissolved.

Example 2 Palladium chloride 0.51 mmol / L, cupric chloride 50.3 mmol / L, copper acetate 6.7
Mmol / L and magnesium acetate 57 mmol / L
Is supplied under the condition of 5.2 L / hr, carbon monoxide is 325 NL / hr, oxygen is 236 NL / hr and carbon dioxide is 2208 NL / h.
Example 1 except that the reaction temperature is 115 ° C.
The reaction was carried out in the same manner as in.

The density of methanol at 115 ° C. is 0.
Since it was 695 g / cc, the retention time T of the liquid was calculated to be 30 minutes.

When the reaction was carried out under such conditions, the production rate of dimethyl carbonate was 2.18 mol / L / hr.
In addition, the reaction liquid extracted from the reactor is a green transparent liquid, and the solid substance believed to be palladium black is
It could not be visually confirmed. The concentration of palladium dissolved in the reaction solution was 62 ppm, and 100% of the palladium component charged into the reaction system was dissolved.

Example 3 Palladium chloride 0.22 mmol / L, cupric chloride 50.3 mmol / L, copper acetate 6.7
Mmol / L and magnesium acetate 57 mmol / L
Is supplied under the condition of 5.2 L / hr, carbon monoxide is 487 NL / hr, oxygen is 358 NL / hr, and carbon dioxide is 2230 NL / h.
Example 1 except that the reaction temperature is 135 ° C.
The reaction was carried out in the same manner as in.

The density of methanol at 135.degree.
Since it was 669 g / cc, the retention time T of the liquid was calculated to be 29 minutes.

When the reaction was carried out under such conditions, the production rate of dimethyl carbonate was 3.55 mol / L / hr.
In addition, the reaction liquid extracted from the reactor was a green transparent liquid, and a solid substance considered to be palladium black was extremely mixed, but the results of atomic absorption analysis showed that the palladium component charged to the reaction system was used. Of 100% was dissolved.

Comparative Example Palladium chloride 0.34 mmol /
L, cupric chloride (50.3 mmol / L), copper acetate (6.7 mmol / L) and magnesium acetate (57 mmol / L) were dissolved in methanol under the condition of 2.0 L / hr and carbon monoxide was added. 314 NL / hr, oxygen 1
86 NL / hr and carbon dioxide 1523 NL / hr
The reaction was performed in the same manner as in Example 1 except that the reaction temperature was 140 ° C.

The density of methanol at 140 ° C. is 0.
Since it was 662 g / cc, the liquid retention time T was calculated to be 75 minutes.

When the reaction was carried out under such conditions, the production rate of dimethyl carbonate was 1.77 mol / L / hr.
Further, the reaction liquid extracted from the reactor was a black turbid liquid, and a large amount of palladium black was observed. The concentration of palladium dissolved in the reaction solution is 2 pp.
m, only 4% of the palladium component charged to the reaction system
Was dissolved, and 96% was precipitated as palladium black.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a reactor used in Examples.

Claims (3)

[Claims] 1. A method for producing a carbonic acid ester by reacting alcohol, carbon monoxide and oxygen in a liquid phase, which comprises a platinum group compound, a weak acid salt or halide of copper, and a weak acid salt of an alkaline earth metal or A method for producing a carbonate ester, which comprises reacting a liquid in a reactor for a residence time of 60 minutes or less in the presence of a catalyst composed of a halide. 2. The method for producing a carbonic acid ester according to claim 1, wherein the reaction temperature is 100 to 140 ° C. 3. The method for producing a carbonate ester according to claim 1, wherein the alcohol containing the catalyst and the raw material gas are continuously fed and reacted to take out the reaction liquid and the gas continuously from the reaction system.