JPH0672966A - Production of carbonate diester - Google Patents

Abstract

PURPOSE:To efficiently obtain the subject compound useful as a raw material for medicines, agri chemicals, etc., in high selectivity and in a high yield by subjecting carbon monoxide and a nitrite ester to a gas phase catalyst contact reaction in the presence of a specific solid catalyst. CONSTITUTION:Carbon monoxide and a nitrite ester are subjected to gas phase catalyst contact reaction to provide the objective compound in the presence of a solid catalyst produced by carrying a palladium ammine chromate complex and one or more kinds of metals (compounds) selected from the group consisting of copper, iron, bismuth, cobalt, nickel and tin on a carrier.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a method for producing a carbonic acid diester from carbon monoxide and a nitrite, using a novel catalyst having excellent selectivity.
The present invention relates to a method for producing a carbonic acid diester selectively and stably. Carbonic acid diester is a very useful compound as an organic synthetic raw material for medicines, agricultural chemicals and the like, and as an intermediate for the production of polycarbonate, urethane and the like.

[0002]

Description of the Prior Art As a method for producing carbonic acid diesters, a method of reacting phosgene with alcohol has been practiced for a long time, but phosgene is extremely toxic and it is desired not to use it for environmental hygiene. . In addition, since hydrochloric acid is a byproduct of the reaction between phosgene and alcohol, which causes corrosion of the equipment material, it is necessary to select an expensive material and there is an industrial problem.Therefore, a manufacturing method that does not use phosgene is desired. Was there.

Therefore, as a production method without using phosgene, a method of synthesizing a carbonic acid diester from alcohol and carbon monoxide has been studied and proposed in various fields (for example, JP-A-60-75447). , JP-A-63
-72650, JP-A-63-38010, etc.). These are methods of synthesizing a carbonic acid diester in a liquid phase by an oxygen oxidation reaction of an alcohol and carbon monoxide using copper halide, palladium halide, etc. as a catalyst. It has the drawbacks that the carbon dioxide diester selectivity based on carbon oxide is low and that the purification of the carbonic acid diester takes time because of the generation of water. Further, when the carbonic acid diester is produced by the methods disclosed in these patents, a step of separating the product from the catalyst is necessary, which is not necessarily an industrially advantageous method.

As an improved method thereof, for example, a solid catalyst in which a nitrite and carbon monoxide are supported on a platinum group metal or a compound thereof, and an oxidizer containing 10 mol% or more of O ₂ per carbon monoxide are used. JP-A-60-181051 proposes a method for producing a carbonic acid diester, which comprises reacting in the gas phase in the presence of a solvent. However, in this method, in order to suppress the by-production of oxalic acid diester, an oxidizer such as oxygen is coexisted in the above ratio with respect to carbon monoxide, but a considerable amount of oxalic acid is present. Diester is by-produced, the selectivity of carbonic acid diester is low, and the reaction rate is not sufficient. Further, it has a drawback that the activity is greatly reduced. Further, since a mixed gas composed of nitrite, carbon monoxide, alcohol, oxygen and the like used in the reaction is used, there is a problem from the viewpoint of safety and it is not always an industrially satisfactory method.

Further, in the method for producing dimethyl carbonate by catalytically reacting carbon monoxide and methyl nitrite in a gas phase,
As disclosed in JP-A-3-141243 and Japanese Patent Application No. 2-257042, compounds of platinum group metals such as palladium chloride and palladium sulfate and iron, copper, bismuth, cobalt,
At least one selected from the group consisting of nickel and tin
Although a method for producing dimethyl carbonate using a catalyst in which a compound of a metal of a kind is supported on a carrier such as activated carbon is disclosed, the life is not yet sufficient.

[0006]

[Problems to be Solved] As described above, in the known method for producing a carbonic acid diester using a nitrite, the reaction rate between carbon monoxide and the nitrite is not sufficient, and the selectivity of the carbonic acid diester is high. Since it is also low, there is a drawback that the purification treatment of the produced carbonic acid diester becomes complicated. Furthermore, there is a problem that the range of concentration of nitrite used in the reaction system exceeds the explosion limit, which is dangerous in operation. Therefore, an object of the present invention is to provide a gas phase method that facilitates separation and recovery of reaction products.
An object of the present invention is to provide an industrially suitable method for producing a carbonic acid diester, which is capable of stably producing a carbonic acid diester with a high selectivity under mild reaction conditions. In particular, in a practical fixed bed gas phase process, it is important that the catalyst activity is stable for a long period of time, and the present invention provides a method for producing a carbonic acid diester that meets such a demand. is there.

[0007]

In order to overcome the above-mentioned problems in the conventionally known method for producing a carbonic acid diester, the present inventors have proposed a carbon dioxide reaction by a gas phase catalytic reaction between carbon monoxide and a nitrite ester. In order to improve the catalyst for producing the diester, as a result of diligent studies on the synthetic reaction of the carbonic acid diester by using the nitrite, as a result of using the solid catalyst as described above under mild reaction conditions, an extremely high yield can be obtained. Moreover, the inventors have reached the present invention by discovering that the carbonic acid diester of the desired product can be obtained with a small decrease in activity.

That is, the present invention provides a solid catalyst in which a palladium ammine chromate complex and a compound of at least one metal selected from the group consisting of iron, copper, bismuth, cobalt, nickel and tin are supported on a carrier. The present invention relates to a method for producing a carbonic acid diester, which comprises reacting carbon monoxide and a nitrite ester in a gas phase.

Examples of the nitrite used in the present invention include methyl nitrite, ethyl nitrite, n- (or i-) propyl nitrite, n- (or i-) butyl nitrite,
Nitrate esters of lower aliphatic monohydric alcohols having 1 to 4 carbon atoms such as sec-butyl nitrite, nitrite esters of alicyclic alcohols such as cyclohexyl nitrite, benzyl nitrite and phenylethyl nitrite. Preferable examples include nitrites of alkyl alcohols, and the nitrites of lower aliphatic monohydric alcohols having 1 to 4 carbon atoms are particularly preferable, and methyl nitrite and ethyl nitrite are most preferable.

The solid catalyst used in the present invention is
Palladium ammine chromate (first catalyst component),
The carrier is loaded with a compound (second catalyst component) of at least one metal selected from the group consisting of iron, copper, bismuth, cobalt, nickel and tin. The chemical formula used in the present invention is, for example, Pd (NH ₃ ) ₄ CrO.
Palladium ammine chromate represented by ₄ or the like is obtained by adding a palladium salt and a chromate in an ammoniacal aqueous solution,
The molar ratio of chromate to palladium salt is 0.2 to
It is obtained by reacting at a ratio of 5.0.
The palladium ammine chromate of the present invention can be obtained, for example, by the reaction represented by the following formula. PdCl ₂ + K ₂ CrO ₄ + 4NH ₃ − → [Pd (NH ₃ ) ₄ ] CrO ₄ + 2KCl

The palladium salt used in the synthesis of palladium ammine chromate is a halide or nitrate, sulfate, or acetate of palladium chloride, palladium bromide, palladium iodide, palladium fluoride, particularly preferably palladium chloride. , Palladium bromide, palladium nitrate,
Palladium sulfate is used. Chromate is N
Alkali metal salts or ammonium salts of a, K, etc., but sodium chromate, potassium chromate, ammonium chromate, sodium dichromate, potassium dichromate, and ammonium dichromate are particularly preferably used. Since the above reaction proceeds quantitatively, it is most desirable to set the molar ratio of the chromate to the palladium salt to 1, but its excess or deficiency does not become an essential problem unless it deviates from the above range.

Examples of the solvent used in this reaction include aqueous solutions of various ammine compounds capable of dissolving palladium salts and chromates. Ammonium compounds used herein include ammonia and organic ammonium compounds such as monomethylammonium, dimethylammonium, trimethylammonium, and ethylenediamine,
N, N dialkylethylenediamine, N, N, N ',
An organic diamine compound such as N'tetraalkylethylenediamine may be mentioned. The concentration of ammonium compound is 1
25 wt% is used, particularly preferably 2-14 wt
% Is used. When the above organic diamine compound is used, it is preferably equimolar to palladium used. It is desirable that the amount of the solvent used be equal to or more than the amount required to completely dissolve the palladium salt and the chromate salt. Also,
The method of adding the raw materials when carrying out the reaction is not particularly limited, for example, a solution prepared by dissolving a palladium salt in an ammoniacal aqueous solution, at the same time, gradually added to an ammoniacal water solvent, or to the solution of the palladium salt. It is preferred to add the chromate solution gradually.

The reaction temperature may be below the boiling point of water,
Generally, -10 to 100 ° C, preferably 10 to 100 ° C
The temperature may be within the range of. The reaction is generally carried out at normal pressure, but it can also be carried out under pressure. The reaction time varies depending on the reaction temperature, the reaction scale, and the stirring conditions, but generally it may be in the range of 5 minutes to 5 hours. Under the above reaction conditions, when the molar ratio of the chromate salt to the palladium salt is 1, the reaction product mixture is composed of the target product, the ammonium salt and the ammonium-based aqueous solvent, and the target product is almost the solvent at room temperature or lower. Since it does not dissolve and exists as a precipitate, the desired product can be isolated by filtration.

The compounds of metals such as iron, copper, bismuth, cobalt, nickel and tin are halogen compounds such as chlorides, bromides, iodides and fluorides of these metals, nitrates, sulfates, phosphates and acetic acid. Inorganic salts such as salts and organic salts are preferable, and among them, the above-mentioned halogen compounds or sulfates are particularly preferable. Suitable examples of the carrier that supports the metal compound as described above include diatomaceous earth, activated carbon, silicon carbide, titania, alumina, and silica-alumina, but activated carbon is most preferable. The method of loading each of the above catalyst components on the carrier does not have to be special, and is a commonly used method, that is, an impregnation method (immersion adsorption method), a kneading method, a deposition method, an evaporation dryness method, a coprecipitation method. Etc. may be used, but in the present invention, it is preferable that they are prepared by an impregnation method or an evaporation-drying method because they are simple. In addition,
The loading of the above catalyst components on the carrier may be carried out simultaneously or sequentially.

The amount of the palladium ammine chromate supported on the carrier is usually 0.1 to 10% by weight, especially 0.5 to 2% by weight of the carrier in terms of palladium metal.
Weight percent is preferred. In addition, the supported amount of a compound of a metal such as iron, copper, bismuth, cobalt, nickel or tin is 0.1 to 50 g atom equivalent, preferably 1 to 10 g, based on palladium in terms of the amount of these metals. Atomic equivalents are preferred.

The solid catalyst used in the present invention contains, as described above, a compound of at least one metal selected from the group consisting of iron, copper, bismuth, cobalt, nickel and tin, in addition to palladium ammine chromate. Although they are supported on a carrier, in the present invention, the compounds of these metals play a co-catalyst function, and by supporting the compounds of these metals in the above amounts on the carrier, palladium ammine chromate alone is supported. The reaction rate of carbon monoxide and nitrite is significantly improved as compared with the above case.

Further, in the present invention, the above-mentioned catalyst is used in the form of powder, granules, or molded bodies, but the size thereof is not particularly limited, and in the case of powder, it is usually used. Those having a particle size of 20 to 100 μm, and in the case of particles, those having a mesh size of 4 to 200 mesh and generally used are suitable. Further, in the case of a molded product, a molded product having a size of several mm is preferably used. Further, one of the features of the present invention is that the catalytic reaction between carbon monoxide and nitrite can be carried out under extremely mild conditions. For example, 0 to
It can be carried out at a temperature of 200 ° C., preferably 50-140 ° C. and normal pressure. Of course, a pressurized system can be used without any problem, and the pressure is 1 to ²⁰ kg / cm ² G and 50 to 14 kg.
It can be carried out in the temperature range of 0 ° C.

In the present invention, it is desirable that the carbon monoxide and the nitrite ester of the raw material gas be diluted with an inert gas such as nitrogen gas and fed to the above-mentioned reactor. Is not particularly limited. However, from the viewpoint of safety, the concentration of the nitrite is 20% by volume or less, preferably 5 to 20%.
It is desirable that the content is% by volume. Accordingly, it is economically preferable that the concentration of carbon monoxide be in the range of 5 to 20% by volume.

That is, considering an industrial manufacturing process, it is preferable to circulate and use a gas such as carbon monoxide and a nitrite ester to be subjected to the reaction, and to purge a part of the circulated gas out of the system. Since the one-pass conversion of carbon monoxide is about 20 to 30%, even if the concentration of carbon monoxide is higher than 20% by volume, the loss only increases, and if it is lower than 5% by volume. There are problems such as reduced productivity. However, if this economic efficiency is ignored, the concentration of carbon monoxide can actually be up to 80% by volume. That is, it is possible to feed the nitrite in a form diluted with carbon monoxide instead of the inert gas.

Therefore, the ratio of carbon monoxide to nitrite used is in the range of 0.1 to 10 mol, preferably 0.25 to 2 mol, of carbon monoxide per 1 mol of nitrite. Is desirable. Further, in the present invention, the space velocity of the gas containing carbon monoxide and the nitrite ester fed to the reactor is 500 to 20,000.
range of hr ⁻¹ , preferably 2000 to 15000 hr
It is desirable to carry out in the range of ^-1 . Further, in the production method of the present invention, the nitrite ester is decomposed to generate nitric oxide (NO) after being involved in the reaction, but the NO is recovered from the reaction gas discharged from the reactor. Then
It is preferable to react with oxygen and the alcohol corresponding to the nitrite to convert the nitrite to the nitrite again, and then to reuse.

[0021]

EXAMPLES Next, the method of the present invention will be specifically described with reference to Examples and Comparative Examples, but these do not limit the method of the present invention in any way. The space-time yield (STY) Y (g / l · h) in each Example and Comparative Example
r) is the contact reaction time between carbon monoxide and nitrite, θ (hr), and the amount of carbonic acid diester formed during that is a (hr).
(G), and the filling amount of the catalyst into the reaction tube was set to b (l), and it was determined by the following equation.

[0022]

[Equation 1]

The activity reduction coefficient D _a (hr ⁻¹ ) in each of the Examples and Comparative Examples is the space-time yield Y at the initial stage of the reaction (after 2 hours from the start of the reaction) under the predetermined reaction conditions.
_{It was} calculated by the following equation between _o (g / l · hr) and the space-time yield Y _t (g / l · hr) after the lapse of t hours from the start of the reaction.

[0024]

[Equation 2]

[Catalyst Preparation Method] Palladium chloride (PdCl
₂ ) 0.178 (1 mmol), potassium dichromate 0.147 g (0.5 mmol) and cupric chloride.2
0.340 g (2 mmol) of the hydrate was dissolved in 40 ml of a 5 wt% aqueous ammonia solution at 80 ° C. by heating to dissolve “Pd, Cr
And Cu-containing solution "was prepared. Granular activated carbon 10
g was immersed and stirred for 1 hour. After that, the catalyst was manufactured by evaporating off at 80 ° C. under reduced pressure, and further drying at 200 ° C. in a nitrogen atmosphere. The loading amount of the metal compound in the catalyst was 1% by weight of Pd as a metal with respect to the carrier, and Pd; Cr; Cu.
= 1; 1; 2 (atomic ratio).

[Synthesis of dimethyl carbonate] The above catalyst 2.5
20 ml inner diameter gas phase reaction tube (with external jacket)
Then, the reaction tube was fixed vertically, a heating medium was circulated in the reaction tube jacket, and heating was controlled so that the temperature in the catalyst layer became 120 ° C. From the upper part of the reaction tube, a mixed gas of carbon monoxide and a gas containing methyl nitrite synthesized from nitric oxide, oxygen and methanol, that is, methyl nitrite; 8% by volume, carbon monoxide; 8% by volume, Nitric oxide; 3% by volume, methanol; 10% by volume and nitrogen; 7
A mixed gas having a composition of 1% by volume was used for 8500 hr ^−1.
Was supplied at the space velocity (GHSV) and reacted under normal pressure. Then, the reaction product passing through this reaction tube was passed through ice-cooled methanol and collected. As a result of analyzing the obtained collected liquid by gas chromatography, the STY of dimethyl carbonate 2 hours after the start of the reaction was 305 g / l.
and the STY of dimethyl carbonate 8 hours after the start of the reaction was 268 g / l · hr. As a result, decrease in activity coefficient _{D a} was 1.5% ^{hr -1.}

Comparative Example 1 [Production of catalyst] Palladium chloride (PdCl ₂ ) 0.17
8 g (1 mmol) and cupric chloride (CuCl ₂ 2H ₂
O) 0.340 g (2 mmol) of methanol solution 40
It was dissolved by heating at 40-50 ° C in ml, and to this, Example 1 was added.
The same granular activated carbon as above was immersed and stirred for 1 hour. afterwards,
Evaporate and remove at 50 ° C under reduced pressure, then 200 ° C in nitrogen atmosphere.
And dried to prepare a catalyst. The composition of the obtained catalyst was Pd.
Cl ₂ —CuCl ₂ / C (activated carbon), and the supported amount of the metal compound in the catalyst is such that Pd is 1 as a metal with respect to the carrier.
% By weight, and Pd: Cu = 1: 2 (atomic ratio).

[Synthesis of Dimethyl Carbonate] Dimethyl carbonate was synthesized in the same manner as in Example 1 except that the above catalyst was used. As a result of analyzing the obtained collected liquid by gas chromatography, STY of dimethyl carbonate was 518 g / l · hr 2 hours after the start of the reaction, and STY of dimethyl carbonate 8 hours after the start of the reaction was 267 g / l · hr. It was hr. As a result, decrease in activity coefficient _{D a} is 8.3% ^{hr -1}
Met.

Examples 2 to 5 and Comparative Example 2 [Production of catalyst] In each of Examples 2 to 5 and Comparative Example 2,
According to the method of Example 1, a compound prepared by preparing a palladium ammonium complex, and further, a compound of at least one metal selected from iron, copper, bismuth, cobalt, nickel and tin is supported on a carrier, A solid catalyst having the catalyst composition and the atomic ratio of the metals of the catalyst components shown in Table 1 was prepared.

[Synthesis of dimethyl carbonate] In each of Examples 2 to 5 and Comparative Example 2, dimethyl carbonate was synthesized in the same manner as in Example 1 except that the above catalyst was used. The results are shown in Table 1.

[0031]

[Table 1]

[0032]

As described above, according to the method of the present invention, the known method for producing a carbonic acid diester by a gas phase catalytic reaction of carbon monoxide and a nitrite is sufficiently satisfactory in the reaction rate. In addition, the selectivity of carbonic acid diester is low, there is a drawback that the operation of separating and purifying carbonic acid diester from the reaction product is complicated, and further, there was a problem that the operation is dangerous. Carbon monoxide and nitrite, a palladium ammine chromate complex, and at least one metal selected from the group consisting of copper, iron, bismuth, cobalt, nickel and tin, or a metal thereof or a compound of those metals. By carrying out a gas phase reaction in the presence of a catalyst supported on a carrier under conditions of low temperature and low pressure, high selectivity can be achieved under mild conditions without risk of operation. Rate, and, in which an effect capable of providing a process for producing a carbonic diester stable.

Claims (1)

[Claims] 1. A palladium ammine chromate complex,
In the presence of a solid catalyst having at least one metal selected from the group consisting of copper, iron, bismuth, cobalt, nickel, and tin, or a compound of these metals supported on a carrier, carbon monoxide and nitrite ester A process for producing a carbonic acid diester, which comprises subjecting the above to a gas phase catalytic reaction.