JP3088868B2 - Method for producing carbonic acid diester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a carbonic diester by reacting alcohols, carbon monoxide and oxygen in the gas phase in the presence of a solid catalyst.

[0002]

2. Description of the Related Art Carbonic diesters are used as additives and organic solvents for gasoline and in the production of fine chemicals such as various carbonates, carbamates, urethanes, pharmaceuticals and agricultural chemicals. It is a compound useful as a reactant in place of

As a method for producing a carbonic diester, a method of reacting phosgene with alcohols has been industrially employed. However, this method requires the use of highly toxic phosgene, and a large amount of highly corrosive hydrochloric acid is produced as a by-product due to the reaction between alcohol and phosgene.

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

The reaction using a palladium catalyst is described in JP-B-61-8816 and JP-B-61-433.
No. 38 discloses this. In this method, a palladium compound is used as a main catalyst, and a copper compound and an alkali metal compound are used in combination. The palladium compound has a high activity and has an advantage that the reaction proceeds rapidly even under a condition of a low carbon monoxide partial pressure, but has a disadvantage that oxalic acid is by-produced.

On the other hand, regarding the reaction using a copper-based catalyst,
It is disclosed in Japanese Patent Publication No. 56-8020. The copper-based catalyst has a simple catalyst composition and has no oxalic acid by-product, but has lower activity than the palladium-based catalyst, requires a large amount of the catalyst, and requires a high carbon monoxide partial pressure.

[0007] Regardless of the palladium-based or copper-based catalyst system, since the reaction solution in which the catalyst is dissolved exhibits strong corrosiveness, a pressure-resistant coating film provided with a corrosion-resistant protective film such as a glass lining or hollow roller lining. Containers need to be used. Since there is a limit in the size of the pressure-resistant container provided with the corrosion-resistant lining, it is difficult to industrially produce a large amount of diester carbonate in the liquid phase using the above-mentioned catalyst.

In order to avoid such a corrosion problem accompanying the liquid phase reaction, there has been proposed a method for producing a carbonic acid diester by reacting alcohol, carbon monoxide and oxygen in a gas phase using a solid catalyst. . For example, JP-T-63-503
No. 460 (WO 87/07601) discloses a catalyst in which a metal halide is supported on a carrier by an impregnation method.
A method is disclosed in which all the raw material components are reacted in the gas phase. In addition, International Publication WO 90/15791 discloses that
A method using a catalyst in which a copper-tertiary organic phosphorus compound complex is supported on activated carbon is disclosed.

However, in the production method by the gas phase reaction, the raw material alcohol is changed into acetal such as formate or methylal, or water by-produced in the reaction reacts with carbon monoxide and oxygen to form carbon dioxide. And the selectivity of carbonic acid diester based on alcohol and carbon monoxide is low. Therefore, not only does the raw material cost increase, but also it is necessary to treat by-products, which can be a very serious problem in producing a large amount of carbonic diester.

In the above-mentioned gas phase reaction, particularly when a copper chloride-based catalyst is used, water produced as a by-product of the reaction reacts with copper chloride to produce a compound having an attacamite structure. Therefore, the catalytic activity gradually decreases, and it is impossible to stably produce a carbonic acid diester for a long period of time.

Accordingly, an object of the present invention is to provide a method capable of producing a large amount of diester carbonate with a high selectivity while maintaining high catalytic activity for a long period of time by using a gas phase method having low corrosiveness.

[0012]

The present inventors have conducted intensive studies in order to achieve the above object, and as a result, as a catalyst for reacting alcohol, carbon monoxide and oxygen in the gas phase, the catalyst component has an average pore diameter of 30 to 30% . Using a solid catalyst supported on a carrier of about 100 angstroms, it has been found that a diester carbonate can be produced with extremely high selectivity while maintaining high catalytic activity for a long period of time with little corrosion.

That is, the present invention relates to a method for producing a carbonic acid diester by reacting an alcohol, carbon monoxide and oxygen in the gas phase in the presence of a solid catalyst, wherein the catalyst component has an average pore diameter of about 30 to 100 angstroms. The present invention provides a method for producing a carbonic acid diester using a solid catalyst supported on a carrier.

The alcohol includes a compound having one or more hydroxyl groups in a molecule, for example, methanol,
Ethanol, 1-propanol, 2-propanol, 1
-Saturated aliphatic alcohols such as butanol; unsaturated aliphatic alcohols such as allyl alcohol; alicyclic alcohols such as cyclohexanol; aromatic alcohols such as benzyl alcohol and phenol; polyhydric alcohols such as ethylene glycol and polyethylene glycol. included. In addition, the aromatic alcohol is used to include phenols having a phenolic hydroxyl group.

Preferred alcohols are monovalent saturated or unsaturated alcohols, for example, alcohols having about 1 to 6 carbon atoms. Particularly preferred alcohols include methanol,
It contains ethanol and the like, and methanol is especially popular.

The main feature of the present invention is that a solid catalyst in which a catalyst component is supported on a carrier having an average pore diameter of about 30 to 100 Å is used.

The catalyst component is not particularly limited as long as it is a catalyst component used as a catalyst for the oxidative carbonylation reaction, and examples thereof include halides, salts, and complexes of transition metals such as copper, iron, nickel, and cobalt. No. These catalyst components can be used alone or in combination of two or more. Also, alkali metal compounds such as lithium chloride, sodium chloride and potassium fluoride; magnesium chloride,
It can also be used in combination with alkaline earth metal compounds such as calcium chloride, strontium bromide and barium sulfate.

Among the above-mentioned catalyst components, a copper compound is preferably used in view of catalytic activity, reaction selectivity, catalyst life and the like. Copper compounds include cuprous fluoride, cuprous chloride, cuprous bromide, cuprous halide of cuprous iodide; cupric fluoride, cupric chloride, cupric bromide Cupric halide of cupric iodide; inorganic acid salts such as copper sulfate, copper nitrate, and copper carbonate; organic acid salts such as copper formate, copper acetate, copper pivalate, and copper benzoate; copper phenoxide and the like Phenol salts; copper alkoxy halides such as methoxy copper chloride, copper methoxy bromide, and ethoxy copper chloride; copper carbonyl halides such as copper carbonyl chloride; copper alkoxy carbonyl halides such as copper methoxy carbonyl chloride; And a complex with a coordinating compound. Examples of the coordinating compound include amines such as ethylenediamine, nitrogen-containing heterocyclic compounds such as imidazole and pyridine, organic phosphorus compounds such as triphenylphosphine, and nitriles such as benzonitrile.

Among the above copper compounds, copper compounds containing one halogen atom per copper atom, such as the above-mentioned cuprous halides, copper alkoxyhalides, copper carbonyl halides, copper alkoxycarbonyl halides, and complexes thereof, are frequently used. Used. When a copper compound containing one halogen atom per copper atom is used as a catalyst component, not only high catalytic activity but also deterioration of the catalyst due to release of halogen, corrosion,
Less likely to hinder the reaction. Therefore, extremely high activity is maintained for a long time, and the carbonic acid diester can be stably produced without corrosion of the apparatus.

In the method of the present invention, the average pore size is from 30 to 10
A carrier of about 0 Å is used. The preferred average pore size is 35-100 Å, especially 35-
It is about 60 angstroms. If the average pore diameter of the carrier is less than 30 angstroms, the selectivity based on carbon monoxide of the carbonic diester decreases. If the average pore size exceeds 100 angstroms, the catalytic activity tends to decrease.

In the present invention, since a carrier having an average pore diameter of about 30 to 100 angstroms is used as a carrier for the solid catalyst, the selectivity of diester carbonate, particularly the selectivity based on carbon monoxide, is remarkably high. This seems to be due to the following reasons.

When the reaction is carried out in the gas phase using a solid catalyst,
The diffusion of gas in the pores of the catalyst often determines the reaction speed and selectivity. In the method of the present invention, the alcohol, carbon monoxide and oxygen react to produce carbonic diester and water. Water is easily adsorbed on a carrier such as activated carbon and has a high boiling point. Therefore, if the pore size of the carrier is small,
Water generated inside the pores is difficult to diffuse and easily accumulates.
As a result, water present in the vicinity of the catalyst component easily reacts with carbon monoxide and oxygen to generate carbon dioxide, and side reactions are likely to occur, and the selectivity based on carbon monoxide of the carbonic diester decreases, and carbon monoxide decreases. Usage rate deteriorates. On the other hand, when a carrier having an average pore diameter of 30 Å or more is used as in the present invention, the diffusion rate of water in the pores is large, and water is quickly released from the inside of the catalyst pores. It is thought that the selectivity based on carbon monoxide is significantly improved.

With respect to the pore volume of the carrier, the pore diameter is 200
The pore volume of pores smaller than Å is preferably at least 40%, particularly preferably about 50 to 90%, based on the pore volume of all pores.

The specific surface area of the carrier is not particularly limited.
Usually 500 m ² / g or more, preferably 700 to 3000
m ² / g, more preferably 900~3000m ² / g
It is about. In the case of activated carbon having a specific surface area of less than 500 m ² / g, the catalytic activity tends to decrease.

Examples of the carrier include activated carbon, alumina, silica, silica-alumina, titania, zirconia, magnesia, silicon carbide, diatomaceous earth, pumice, alundum and the like.
A carrier usually used as a carrier for a solid catalyst can be used. Among these carriers, activated carbon is particularly used. When activated carbon is used as a carrier, the carbon monoxide partial pressure becomes
For example, a sufficiently high reaction rate can be obtained even at a low pressure of 20 atm or less.

The solid catalyst of the present invention comprises a catalyst component as a carrier,
It may be prepared in one or more stages by supporting it by a method such as an impregnation method, a coating method, or an adsorption method, or prepared by molding a catalyst component by using an appropriate binder by tableting, extrusion, or the like. May be. The shape of the solid catalyst is not particularly limited, and may be any of a sphere, a column, a needle, and the like.

The amount of the catalyst component carried on the carrier can be appropriately selected within a range that does not impair the catalytic activity, but is usually about 2 to 40% by weight based on the carrier. When the supported amount is less than 2% by weight based on the carrier, the catalytic activity tends to decrease. On the other hand, if the loading exceeds 40% by weight, high-dispersion loading becomes difficult, so that the interaction between the carrier and the catalyst component is weakened, and it is difficult to obtain high catalytic activity. The preferable loading amount of the catalyst component is about the saturated adsorption amount of the carrier, and varies depending on the type of the carrier to be used, but is, for example, about 2 to 20% by weight based on the carrier.

The process according to the invention can be carried out in fixed-bed or fluidized-bed reactors. The reaction takes place in the gas phase. The reaction pressure is not particularly limited, but is usually from atmospheric pressure to 6 to 6 in consideration of economical aspects such as equipment costs while obtaining a sufficient reaction rate.
0 atm, preferably about atmospheric pressure to about 30 atm.

The reaction temperature can be selected within a range that does not decrease the reaction rate and suppresses side reactions.
° C, preferably about 80 to 150 ° C.

The composition of the gas supplied to the reaction system can be selected within a range that does not hinder the smooth progress of the reaction. The preferred composition of the gas supplied to the reaction system is such that the alcohol content is 1 to 20% by volume and the carbon monoxide content is 70 to 95% by volume.

In the present specification, the alcohol content, carbon monoxide content and oxygen content mean the volume% of the total amount of the three components of alcohol, carbon monoxide and oxygen in the gas supplied to the reaction system.

When the alcohol content is less than 1% by volume, the reaction rate tends to decrease. On the other hand, when the alcohol content exceeds 20% by volume, the amount of by-products such as formate esters such as methyl formate and ketals such as methylal increases, and the selectivity of diester carbonate tends to decrease.

Further, the carbon monoxide content is 70% by volume.
If it is less than 95%, the amount of the by-products is likely to increase, and if it exceeds 95% by volume, the oxygen content is relatively reduced, so that it is difficult to obtain a sufficient reaction rate.

When the alcohol content and the carbon monoxide content in the gas supplied to the reaction system are set within the above-mentioned preferred ranges, side reactions are suppressed, and the selectivity based on methanol is particularly improved.

The oxygen content in the gas supplied to the reaction system constitutes the balance of alcohol and carbon monoxide, and is usually 0.5 to
It is about 28% by volume, preferably about 1 to 15% by volume.

The supply molar ratio of carbon monoxide to oxygen (C
O / O ₂ ) is, for example, 1 to 200, preferably 1 to 10
It is about 0.

The supply molar ratio of alcohol to oxygen (alcohol / O ₂ ) is, for example, about 0.05 to 20, preferably about 0.1 to 10, and the supply molar ratio of carbon monoxide to alcohol (CO / alcohol). Is usually 1 to 1
00, preferably about 1 to 50.

The gas supplied to the reaction system may be a mixed gas composed of alcohol, carbon monoxide and oxygen.
If necessary, it may be diluted with a gas inert to the reaction, for example, nitrogen, helium, argon, carbon dioxide or the like. In this case, air may be used instead of oxygen, and nitrogen in the air may be used as an inert gas. Alternatively, carbon dioxide produced as a by-product of the reaction may be recycled to the reaction system and used as an inert gas for dilution.

The space velocity of the gas supplied to the reaction system is, for example, 10 to 50,000 h ^-1 , preferably 100 to 50,000 h ^-1 .
It is about 5000 h ^-1 .

[0040]

According to the method of the present invention, a solid catalyst in which a catalyst component is supported on a carrier having an average pore diameter of about 30 to 100 angstroms is used. While maintaining this, the diester carbonate can be produced in large quantities with very high selectivity.

[0041]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 2.9 g of cuprous chloride was supported on 40 g of activated carbon (Kuraray Chemical Co., Ltd., Kuraray Coal BP25) having an average pore diameter of 44 Å and a specific surface area of 2,500 m ² / g using an acetonitrile solvent. And dried under reduced pressure at 130 ° C. to prepare a solid catalyst.

This solid catalyst was used for an inner diameter of 27 mm and a length of 45 mm.
A 0 mm stainless steel reaction tube was filled to a layer length of 35 mm, the reaction temperature was set to 120 ° C., the reaction pressure was set to a gauge pressure of 7 Kg / cm ² , and carbon monoxide was 43.2 normal liter / Hr. Oxygen was passed at a flow rate of 1.74 normal liters / Hr and methanol was flowed at a flow rate of 11.7 g / Hr (8.2 normal liters / Hr), and the reaction was carried out continuously for 4 hours. As a result of analyzing the reaction product from 3 hours to 4 hours after the start of the reaction, 8.0 mol% of the charged methanol was converted to dimethyl carbonate, the selectivity based on carbon monoxide was 91%, and the selectivity based on methanol was 91%. Was 99%. The production rate of dimethyl carbonate was 0.8 mol / Hr per liter of the catalyst.

Comparative Example 1.9 g of cuprous chloride was added to 40 g of activated carbon (Shirasagi C2X 4 / 6-2, manufactured by Takeda Pharmaceutical Co., Ltd.) having an average pore diameter of 17 angstroms and a specific surface area of 1000 m ² / g, and an acetonitrile solvent. And dried under reduced pressure at 130 ° C. to prepare a solid catalyst. In order to compare the catalyst performance under a constant space velocity (SV) condition, the catalyst was prepared so that the amount of cuprous chloride carried per unit volume was equal to that of the solid catalyst of the example.

The reaction was carried out for 4 hours in the same manner as in Example except that this solid catalyst was used. As a result of analyzing the reaction product from 3 hours to 4 hours after the start of the reaction, 8.5 mol% of the charged methanol was converted to dimethyl carbonate, the selectivity based on carbon monoxide was 72%, and the selectivity based on methanol was 72%. Is 9
4%. The production rate of dimethyl carbonate was 0.78 mol / Hr per liter of the catalyst.

Continuation of the front page (56) References JP-A-6-285375 (JP, A) JP-A-5-255199 (JP, A) JP-A-3-190846 (JP, A) , A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 68/00 C07B 61/00 300

Claims (4)

(57) [Claims] 1. A method for producing a carbonic acid diester by reacting an alcohol, carbon monoxide and oxygen in the gas phase in the presence of a solid catalyst, wherein the catalyst component has an average pore diameter of 30 to 10
0 Ong method for producing a carbonic acid diester using a solid catalyst supported on a carrier Strom. 2. The method for producing a carbonic acid diester according to claim 1, wherein activated carbon is used as a carrier. 3. The method according to claim 1, wherein a solid catalyst having a copper compound supported on a carrier is used as the catalyst component. 4. The process for producing a carbonic acid diester according to claim 3, wherein a copper compound containing one halogen atom per copper atom is used.