JPH0819053B2 - Method for producing carbonic acid diester - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a carbonic acid diester, and more particularly to a method for producing a carbonic acid diester by a gas phase method using a catalyst containing a halogen as a catalyst component, which is a long-term process without corroding the apparatus. The present invention relates to a method for producing a carbonic acid diester that can stably produce a carbonic acid diester over a period of time.

[0002]

BACKGROUND OF THE INVENTION Carbonic acid diesters such as dimethyl carbonate are widely used as extenders for gasoline, octane number improvers and organic solvents, and in recent years produce isocyanates, polycarbonates and various pharmaceuticals, agricultural chemicals and the like. At the same time, it is used as an alternative raw material for phosgene, and its application is expanding more and more.

Such carbonic acid diesters have been conventionally produced by a method of reacting phosgene with an alcohol. However, phosgene is highly toxic, and this reaction causes hydrochloric acid as a by-product to corrode the equipment. There is. For this reason, a method for producing a carbonic acid diester without using phosgene has been developed. For example, JP-A-54-24827 discloses that alcohol, carbon monoxide and oxygen in a liquid phase in the presence of a copper halide catalyst. A method for producing a carbonic acid diester to react is disclosed. Furthermore, a liquid phase method using a copper-based or palladium-based catalyst containing halogen as a catalyst component is disclosed in JP-A-50-40528, JP-B-61-8816, and JP-A-62-81356. It is disclosed in Japanese Patent Laid-Open No. 1-287062. However, such a liquid phase method has solved the point of toxicity as compared with the method using phosgene, but (1)
Since the catalyst halide is used in solution, the reactor will be corroded, (2) water generated during the reaction will significantly reduce the catalytic activity, and (3) carbonic acid diester from the reaction mixture obtained by the reaction. There are problems that it takes time and effort to separate them, and it is difficult to separate the catalyst dissolved in the reaction mixture. In particular, in order to prevent corrosion of the reaction device, it is necessary to construct the device using a high-grade material resistant to corrosion, which increases the cost of constructing the device and may cause an accident due to the corrosion of the device.

As an alternative method to the liquid phase method, a method of producing a carbonic acid diester by a gas phase reaction is disclosed in, for example, Japanese Patent Publication No. 63-503460, JP-A-4-89.
No. 458, International Application Publication No. WO90 / 15791, etc.

In the vapor phase methods disclosed in these publications, an alcohol is reacted with carbon monoxide and oxygen in the vapor phase using a catalyst in which a copper-based or platinum-based halide is supported on a porous carrier. After the obtained reaction product gas is taken out from the reactor, it is cooled and separated into a condensed liquid and an uncondensed gas, and carbonic acid diester is obtained as a reaction product from the condensed liquid.

According to such a vapor phase method, the problems associated with the liquid phase method described above are almost eliminated. However, according to the study by the present inventors, in such a gas phase method,
Since halogen is scattered from the catalyst component supported on the porous carrier, if carbonic acid diester is produced for a long period of time, at least a part of reaction products such as a cooler and a gas-liquid separator will be produced. Where exists in the liquid state,
It was found that the device was corroded. For this reason,
It has been desired to develop a method for producing a carbonic acid diester that does not corrode the equipment even when the carbonic acid diester is produced by a vapor phase method in the presence of a halogen-containing catalyst for a long period of time.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and in the production of carbonic acid diester by a gas phase method in the presence of a catalyst containing halogen as a catalyst component, the apparatus is corroded. It is an object of the present invention to provide a method for producing a carbonic acid diester that can stably produce the carbonic acid diester for a long period of time without causing the reaction.

[0008]

Method for producing a carbonic diester according to the present invention SUMMARY OF THE INVENTION A in the presence of a halogen-containing catalyst, in the gas phase reaction conditions,
React with alcohol, carbon monoxide and oxygen
Or a step of reacting carbon monoxide and a nitrite to form a carbonic acid diester, and bringing the obtained reaction product gas into contact with a solid dehalogenating agent to dehalogenate the reaction product gas It is characterized in that it comprises a step, a step of cooling the dehalogenated reaction product gas to separate it into a condensed liquid and an uncondensed gas, and a step of recovering the carbonic acid diester from the separated condensed liquid.

As the above dehalogenating agent, it is preferable to use an oxide of a metal selected from Group IA, Group II, Group III metals and titanium .

[0010]

DETAILED DESCRIPTION OF THE INVENTION The method for producing a carbonic acid diester according to the present invention will be specifically described below. The method for producing a carbonic acid diester according to the present invention comprises: [I] in the presence of a halogen-containing catalyst, under gas phase reaction conditions ,
React with alcohol, carbon monoxide and oxygen
Or a step of reacting carbon monoxide and a nitrite to produce a carbonic acid diester, and [II] contacting the obtained reaction product gas with a solid dehalogenating agent to remove the reaction product gas. Halogen treatment, [III] cooling the dehalogenated reaction product gas to separate into condensed liquid and uncondensed gas, and [IV] recovering carbonic acid diester from the separated condensed liquid. However, FIG. 1 schematically shows such a process.

The gas phase reactor 1 may be of a fixed bed type, a fluidized bed type or a moving bed type, and the reaction form is not limited. First, in step [I], the reaction raw material introduced into the gas phase reactor 1 through the line 1a is reacted under gas phase reaction conditions in the presence of a halogen-containing catalyst to produce a carbonic acid diester. The reaction system carried out in such step [I] is not particularly limited as long as it is a reaction for producing a carbonic acid diester carried out in the presence of a halogen-containing catalyst. For example, (i) in the presence of a metal halide catalyst such as copper, a reaction of reacting alcohol, carbon monoxide and oxygen to form a carbonic acid diester, (ii) in the presence of a platinum group metal halide catalyst. , A reaction of reacting carbon monoxide and a nitrite.

Examples of the metal halide catalyst used in the present invention in the above (i) reaction system include halide catalysts of copper, nickel, cobalt and the like, and particularly, copper halide or copper halide and other compounds. And the combination.

Examples of such copper halides include monovalent or divalent copper halides, specifically, copper chloride (CuCl, CuCl ₂ ), copper bromide (CuBr, Cu).
Br ₂ ), copper iodide (CuI, CuI ₂ ), and copper fluoride. These may be used alone or in combination. Of these, cupric halide is preferable, and cupric chloride (CuCl ₂ ) is particularly preferable.

Other compounds used in combination with the copper halide include, for example, alkali metal hydroxides or alkaline earth metal hydroxides, tertiary organic phosphorus compounds having a phenyl group or an alkyl group, and I
Examples thereof include halides of metals selected from Group A and Group IIA.

Specific examples of the alkali metal hydroxide or alkaline earth metal hydroxide include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide, barium hydroxide and calcium hydroxide. Alkaline earth metal hydroxides such as They are,
Used alone or in combination.

Examples of the tertiary organic phosphorus compound having a phenyl group or an alkyl group include triphenylphosphine, triphenylphosphite, alkylarylphosphines such as dimethylphenylphosphine, trimethylphosphite, triethylphosphite and the like. Examples include trialkyl phosphite, trimethyl phosphate, trialkyl phosphate such as triethyl phosphate, and the like.

Specific examples of the metal halide selected from Group IA and Group IIA include halides of calcium, sodium, lithium, magnesium, cesium or calcium.

These copper halide catalysts are usually supported on a porous carrier. The surface area of such a porous carrier is usually preferably 30 m ² / g or more. Specific examples include activated carbon, titanium oxide, niobium oxide, silica, zirconium oxide, magnesium oxide and alumina.

In order to support the above-mentioned catalyst component on the porous carrier, an impregnation method, a kneading method, a deposition method, a coprecipitation method or the like is appropriately adopted. The amount of the catalyst component supported on the porous carrier is not particularly limited as long as the obtained catalyst can have activity in the synthesis reaction of carbonic acid diester, but is not particularly limited, and examples thereof include copper halide and alkali metal hydroxide or alkaline earth metal. When supporting in combination with a metal hydroxide,
Copper halide is Cu / (copper halide + porous carrier)
Is preferably loaded in an amount of 1.5 to 20% by weight, more preferably 5 to 15% by weight. In addition, the alkali metal hydroxide or alkaline earth metal hydroxide has a molar ratio ((OH group) / Cu in terms of the hydroxyl group (OH group) equivalent in the hydroxide, relative to the Cu atom in the copper halide. ), Preferably 0.3 to 2, more preferably 0.5 to 1.5.

(I) In the reaction system, alcohol, carbon monoxide and oxygen are reacted in the presence of the above metal halide catalyst to produce carbonic acid diester. Examples of such alcohols include aliphatic alcohols having 1 to 6 carbon atoms, alicyclic alcohols and aromatic alcohols.

Specific examples include monohydric alcohols such as methanol, ethanol, propyl alcohol, butanol, pentanol, hexanol, cyclopropanol, cyclobutanol, cyclopentanol, cyclohexanol and benzyl alcohol. These may be used alone or in combination. Of these,
Particularly, methanol, ethanol and the like are preferable.

In the present invention, when one kind of alcohol is used as an alcohol, a symmetrical carbonic acid diester is obtained, and when different alcohols are used in combination, a symmetrical or asymmetrical carbonic acid diester is obtained.

In the reaction system as described above, carbon monoxide is in a molar ratio with respect to alcohol (CO / alcohol).
And usually about 0.01 to 100, preferably 0.5 to 2
0, more preferably in an amount of 1 to 10, the oxygen is in molar ratio with respect to the alcohol (O ₂ / alcohol), 0.
It is used in an amount of 01 to 2.0, preferably 0.05 to 1.0, more preferably 0.05 to 0.5.

The carbon monoxide and oxygen are usually in a molar ratio (CO / O ₂ ) of 1 to 1000, preferably 10 to 10.
It is used in an amount of 0, more preferably 20 to 50. Oxygen is supplied as pure molecular oxygen or diluted with an inert gas such as nitrogen or argon.

The reaction of the alcohol, carbon monoxide and oxygen as described above may be carried out under the condition that the reaction can be carried out under a vapor phase condition. Specifically, the reaction temperature is usually 70 to 350 ° C., preferably Is 80 to 250 ° C., more preferably 100 to 200 ° C., and the reaction pressure is usually atmospheric pressure to 35 kg / cm ² G, preferably ^{2 to 20} kg / cm ² G, more preferably 5 to 15 kg / cm ² G. Is desirable.

Regarding the reaction system (i) for producing a carbonic acid diester in the presence of a metal halide catalyst such as copper, Japanese Patent Publication No. 63-503460, International Application Publication WO 90/15791, and the present application The details are described in the specification of Japanese Patent Application No. 3-230817 by the applicant.

In step [I], as described above (ii)
Carbon monoxide may be reacted with a nitrite ester in the presence of a platinum group metal halide catalyst to form a carbonic acid diester.

Examples of such a platinum group metal halide catalyst include (a) chlorides of platinum group metals such as palladium, platinum, iridium, ruthenium, rhodium, and (b) iron.
Examples of the solid catalyst include a carrier and a compound of at least one metal selected from copper, bismuth, cobalt, nickel, and tin.

Specific examples of the platinum group metal chloride (a) include palladium chloride, platinum chloride, iridium chloride, ruthenium chloride, rhodium chloride and the like.

Specific examples of the metal compound (b) include iron,
Mention may be made of copper, bismuth, cobalt, nickel or tin halides, nitrates, sulphates, phosphates or acetates.

As the carrier carrying these catalyst components, diatomaceous earth, activated carbon, silicon carbide, titania,
Alumina etc. are mentioned. In order to support the above-mentioned catalyst component on the porous carrier, an impregnation method, a kneading method, a deposition method,
A coprecipitation method or the like is appropriately adopted.

The amount of the catalyst component supported on the porous carrier is not particularly limited as long as the obtained catalyst has an activity in the synthesis reaction of carbonic acid diester, and is not particularly limited, but (a) a platinum group metal chloride The supported amount is usually 0.1 to 10% by weight, preferably 0.5 to 2% by weight, based on the metal, and (b) the metal compound corresponds to the above (a) platinum group metal in terms of the metal. On the other hand, usually 1 to 50 gram atomic equivalent, preferably 1 to
It is 10 grams atomic equivalent.

Examples of the nitrite used as a reaction raw material include methyl nitrite, ethyl nitrite, n- or i-protyl nitrite, n- or i-butyl nitrite, sec-butyl nitrite and the like having 1 carbon atom. To nitrites of lower aliphatic monohydric alcohols, nitrites of alicyclic alcohols such as cyclohexyl nitrite, and nitrites of alalkyl alcohols such as benzyl nitrite and phenylethyl nitrite.

In the gas phase reaction carried out in the presence of such a platinum halide catalyst (ii), specifically, the reaction temperature is usually 0 to 200 ° C., preferably 50 to 120 ° C., and the reaction pressure is Is usually 1 to 20 kg / cm ² G, preferably 2
Performed at ~ 3 kg / cm ² G.

Regarding the reaction system for producing the carbonic acid diester in the presence of the above (ii) platinum halide catalyst,
The details are described in JP-A-4-89458.

The gas phase reaction as described above is carried out by the batch method,
It may be carried out by any of the continuous methods. In the step [I] as described above, the reaction product containing the carbonic acid diester produced in the presence of the halogen-containing catalyst is obtained in a gaseous state.

In the present invention, the reaction product gas is then
In step [II], the reaction product gas is dehalogenated by contact with a solid dehalogenating agent. This dehalogenation treatment step [II] may be carried out under the condition that the reaction product gas can be brought into contact with the solid dehalogenating agent in a state where the reaction product gas is not condensed, that is, in the gas phase reactor 1, for example. Alternatively, it may be carried out in the dehalogenation tower 2 provided in the middle of the line 1b connecting the gas phase reactor 1 and the cooler 3. Alternatively, both of these may be performed. When the dehalogenation treatment is performed in the gas phase reactor 1, a layer made of a solid dehalogenating agent may be provided at the gas phase outlet of the catalyst bed.

The solid dehalogenating agent used in the present invention is not particularly limited as long as it can adsorb and remove the halogen chemically or physically by contacting with a gas containing halogen. Specifically, Group IA, Group II, Group II
Examples thereof include oxides of metals selected from Group I metals and titanium .

Group IA metal oxides such as sodium and potassium, Group II metal oxides such as magnesium, calcium, strontium, barium and zinc, and Group III metal such as boron, aluminum, gallium and indium.
Examples thereof include metal oxides selected from group metal oxides and titanium oxides , or mixed oxides of two or more metals.

More specific examples include calcium oxide, zinc oxide, sodium aluminate, alumina and the like.

These may be used alone or in combination. Of these, alumina, calcium oxide,
Zinc oxide and sodium aluminate are preferably used.

In the present invention, the reaction product gas dehalogenated as described above in step [III] is then cooled and separated into a condensed liquid and an uncondensed gas. In particular,
The reaction product gas dehalogenated in the reactor 1 or the dehalogenation tower 2 is introduced into a cooler (heat exchanger) 3 via a line 1b to be cooled, and then a gas-liquid separator 4 via a line 3a. And is separated into a condensed liquid and an uncondensed gas.

The form of the gas-liquid separator 4 is not limited to a stationary type. Next, in step [IV], the carbonic acid diester is recovered from the condensate separated by the gas-liquid separator 4 as described above. That is, the condensate usually contains by-products, alcohol, and the like, along with the carbonic acid diester, which is the desired reaction product, and is usually guided to the purification step through the line 4a to purify and separate the carbonic acid diester.

On the other hand, gases such as carbon monoxide, oxygen and carbon dioxide are discharged from the line 4b. The gas containing such unreacted carbon monoxide is appropriately used in the gas phase reactor 1.
It can be recycled to the internal reaction system for reuse.

Referring to FIG. 1 referred to above, the reaction system carried out in the step [I] is mainly described in the case where the above-mentioned (i) metal halogen-based catalyst is used to react alcohol, carbon monoxide and oxygen. However, as described above, the present invention is not limited to this example.

Specific examples of the carbonic acid diester obtained in the present invention as described above include dimethyl carbonate, diethyl carbonate, dipropyl carbonate,
Dibutyl carbonate, dipentyl carbonate, dihexyl carbonate, dicyclopropyl carbonate,
Examples thereof include dicyclobutyl carbonate, dicyclopentyl carbonate, dicyclohexyl carbonate, dibenzyl carbonate, methyl ethyl carbonate, methyl propyl carbonate and ethyl propyl carbonate.

[0047]

According to the method for producing a carbonic acid diester according to the present invention, when a carbonic acid diester is produced under a gas phase reaction condition in the presence of a halogen-containing catalyst, the apparatus is stable for a long period of time without being corroded. Carbonic acid diesters can be produced.

Further, according to the present invention, accidents caused by corrosion can be prevented and the carbonic acid diester can be produced with excellent safety. Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

[0049]

【Example】

[Catalyst preparation] (Solution preparation) (1) Add 25.0 g of cupric chloride to 100 ml of distilled water,
An aqueous cupric chloride solution was prepared. (2) 22.3 g of sodium hydroxide was added to 100 ml of distilled water to obtain a sodium hydroxide aqueous solution. (Catalyst preparation) 15 g of activated carbon having a particle size of 1.7 mm to 2.4 mm was impregnated with 8 ml of the above cupric chloride aqueous solution, and then dried at 100 ° C. for 3 hours while circulating an inert gas (nitrogen). . After cooling, the above steps were performed twice more.
Next, 8 ml of the above sodium hydroxide aqueous solution was impregnated into activated carbon carrying cupric chloride, and then dried at 100 ° C. for 3 hours while circulating an inert gas (nitrogen). Thus, the catalyst A [Cu loading amount (Cu weight /
(Weight of copper halide + weight of activated carbon) = 13.5 wt%, OH / Cu (molar ratio) = 1] was obtained.

[0050]

Example 1 Dimethyl carbonate (DMC) was produced as follows using a high pressure fixed bed reactor.

14 ml of catalyst A was filled in a stainless steel reaction tube having an inner diameter of 12 mm, and activated alumina 10 was added to the lower layer of catalyst A.
g. A reaction pressure of 6 kg / cm ² G,
Under the condition of a reaction temperature of 130 ° C., methanol was introduced at a rate of 5 g / hour, carbon monoxide was 57.8 ml / min, and oxygen was introduced at 3.6 ml / min to prepare DMC.

The reaction product (gas) obtained as described above was introduced into a gas-liquid separator and the following corrosion test was conducted. A 20 mm × 20 mm × 2 mm SUS-304 test piece was installed so as to be immersed in the reaction solution in the gas-liquid separator in which the reaction product was induced, and the mass change of the test piece was measured to determine the corrosion rate. It was

The reaction was stopped after 300 hours from the start of the reaction, and the corrosion rate of the test piece was determined. It was below the detection limit and no corrosion was observed.

[0054]

Example 2 In Example 1, 25% CaO-48% ZnO was used in the lower layer of catalyst A instead of 10 g of activated alumina.
D as in Example 1, but with 10 g alumina
MC was manufactured and the same corrosion test as in Example 1 was performed.

The reaction was stopped after 300 hours of reaction, and the corrosion rate of the test piece was determined. As a result, it was below the detection limit and no corrosion was observed.

[0056]

Comparative Example 1 DMC was prepared in the same manner as in Example 1 except that the lower layer of the catalyst A was not filled with anything.
Was manufactured and subjected to the same corrosion test as in Example 1.

The reaction was stopped after 300 hours of reaction, and the corrosion rate of the test piece was determined. As a result, it was 0.8 g / m ² · hr, and corrosion was clearly observed.

[Brief description of drawings]

FIG. 1 schematically shows a process of a method for producing a carbonic acid diester according to the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B01J 27/128 X C07B 61/00 300

Claims (2)

[Claims] 1. An alcohol, carbon monoxide and oxygen are reacted under gas phase reaction conditions in the presence of a halogen-containing catalyst.
Or react with carbon monoxide and nitrite
Generating a are allowed to carbonic acid diester, a step of the resulting reaction product gas to dehalogenation treatment of the reaction product gas by contacting the solid dehalogenating agent, condensed by cooling the dehalogenation treated reaction product gas A method for producing a carbonic acid diester, comprising a step of separating a liquid and an uncondensed gas, and a step of recovering the carbonic acid diester from the separated condensate. 2. The dehalogenating agent is a Group IA, Group II compound.
The method for producing a carbonic acid diester according to claim 1, which is an oxide of a metal selected from Group III metals and Group III metals and titanium .