JP2850859B2 - Method for producing carbonic diester and method for suppressing reduction in activity of catalyst component - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a carbonic acid diester, and more particularly, to a method for selectively producing a carbonic acid diester from carbon monoxide and a nitrite. The present invention also relates to a method for suppressing a decrease in activity during the reaction of the catalyst component used in the method for producing a carbonic acid diester.

[0002]

2. Description of the Related Art Carbonic diester is a very useful compound as a raw material for organic synthesis of pharmaceuticals, agricultural chemicals and the like, and as an intermediate for the production of polycarbonate and urethane.

As a method for producing a carbonic diester, a method of reacting phosgene with an alcohol has been practiced for a long time, but phosgene is extremely toxic, and a large amount of hydrochloric acid is produced by the reaction between phosgene and an alcohol. There is a demand for a production method that does not use phosgene, for example, there is a problem in the material of the apparatus because it produces by-products. For this reason, as a production method using no phosgene, a method of synthesizing a carbonic acid diester from alcohol and carbon monoxide has been studied in various fields and proposed (for example, Japanese Patent Application Laid-Open No. Sho 60-7544).
No. 7, JP-A-63-72650, JP-B-63
Publications such as -38018, WO-87 / 7601 and the like). The methods described in these publications are:
This is a method of synthesizing a carbonic acid diester by using an oxidation reaction of alcohol and carbon monoxide with oxygen using copper halide, palladium halide or the like as a catalyst. However, there is a drawback that the selectivity of carbonic acid diester is low, and the purification of carbonic acid diester is troublesome due to the formation of water.

As an improved method, for example, a solid catalyst in which a nitrite and carbon monoxide are supported on a platinum group metal or a compound thereof (eg, a chloride of a platinum group metal such as palladium chloride) on a carrier is used. A method for producing a carbonic acid diester which is subjected to a gas phase contact reaction by using the same is proposed in JP-A-60-181051. In this production method, an oxidizing agent of 10 mol% or more as O ₂ per carbon monoxide is present in the reaction system. However, in this method, a considerable amount of oxalic acid is used in spite of coexistence of an oxidizing agent such as oxygen with carbon monoxide in the above ratio in order to suppress the by-product of oxalic acid diester. Diester is a by-product,
The selectivity for the carbonic acid diester is low, and the reaction rate is not sufficient. Furthermore, the range of use of nitrite in a mixed gas composed of nitrite, carbon monoxide, alcohol, oxygen, etc., used for the reaction exceeds the explosion limit,
This method is not always satisfactory industrially, for example, there is a problem in terms of safety.

Accordingly, the present inventor has proposed a method for overcoming the above-mentioned problems, in which a platinum group metal or a compound thereof (eg, a chloride of a platinum group metal such as palladium chloride) and iron, copper, bismuth, cobalt, nickel And a method for producing a carbonic acid diester from carbon monoxide and nitrite using a novel solid catalyst in which at least one metal compound selected from the group consisting of tin and tin is supported on a carrier. (Application specification of Japanese Patent Application No. 1-284816 = Japanese Unexamined Patent Application Publication No.
-141243). This method is an excellent method as an industrial process because it has a high reaction rate between carbon monoxide and nitrite and a high selectivity for carbonic acid diester based on carbon monoxide, and is a gas phase reaction.

[0006]

According to the study of the present inventor, according to the study of the present invention, the nitrite ester in the presence of a solid catalyst in which a catalyst component containing a known platinum group metal or a compound thereof is supported on a carrier as described above. When the method of producing a carbonic acid diester by gas phase contact reaction between carbon dioxide and carbon monoxide is carried out using a platinum group metal chloride as a catalyst component, the platinum group metal It has been found that a small amount of chlorine is scattered from the chloride and the catalytic activity is gradually reduced.

Accordingly, an object of the present invention is to provide a diester carbonate with a high selectivity and a high yield under mild reaction conditions by a gas phase method in which the reaction product can be easily separated and recovered. By extending the life of the catalyst in the gas phase contact reaction system between carbon monoxide and nitrite, an industrially suitable method for producing a carbonic acid diester, which enables to produce a carbonic acid diester in a stable state for a long period of time, And a method for suppressing a decrease in the activity of the catalyst component.

[0008]

According to the present invention, a nitrite ester and carbon monoxide are brought into contact in the gas phase in the presence of a solid catalyst in which a catalyst component containing a platinum group metal chloride is supported on a carrier. A method for producing a carbonic acid diester comprising reacting, wherein hydrogen chloride is supplied to the reaction system in an amount necessary for compensating for the chlorine content scattered from the platinum group metal chloride during the reaction. To produce a carbonic acid diester.

The present invention also comprises reacting the nitrite with carbon monoxide in the gas phase in the presence of a solid catalyst having a catalyst component containing a platinum group metal chloride supported on a carrier. In carrying out the method for producing a carbonic acid diester, platinum is supplied to the reaction system by supplying an amount of hydrogen chloride necessary for compensating for the chlorine content scattered from the chloride of the platinum group metal during the reaction. There is also a method of suppressing a decrease in the activity of a catalyst component containing a chloride of a group metal.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. Examples of the nitrite used in the present invention include methyl nitrite, ethyl nitrite, n- (or i-) propyl nitrite, n- (or i-) butyl nitrite, and nitrite se.
Nitrite esters of lower fatty acid monohydric alcohols having 1 to 4 carbon atoms such as c-butyl, nitrites of alicyclic alcohols such as cyclohexyl nitrite, and aralkyl alcohols such as benzyl nitrite and phenylethyl nitrite Preference is given to nitrites and the like, but particularly preferred are the above-mentioned nitrites of lower aliphatic monohydric alcohols having 1 to 4 carbon atoms, among which methyl nitrite and ethyl nitrite are most preferred.

Further, the solid catalyst used in the present invention comprises:
The catalyst component is a chloride of a platinum group metal such as palladium, platinum, iridium, ruthenium, and rhodium, which is supported on a carrier.
As described in the specification of Japanese Patent Application No. 3-141243, a compound of a metal selected from the group consisting of iron, copper, bismuth, cobalt, nickel and tin is used in combination as a catalyst component. Is preferred. Specific examples of the chloride of the platinum group metal include palladium chloride, platinum chloride, iridium chloride, ruthenium chloride and rhodium chloride, among which palladium, ruthenium or rhodium chloride are particularly preferred, and palladium chloride is preferred. Most preferred.

The chloride of the platinum group metal in the present invention is not limited to those introduced as the above-mentioned chlorides, and the above-mentioned chloride or chlorine is converted in the presence of hydrogen chloride. It may be a platinum group metal or a compound of the metal that can form a complex that participates in the reaction. Examples of such platinum group metal compounds include platinum group metal bromates, iodates, halogenates such as fluorates, nitrates, and the like.
Phosphate, acetate, oxalate, benzoate and the like, more specifically, palladium bromide, palladium iodide, palladium fluoride, palladium acetate, palladium phosphate, palladium acetate, palladium oxalate, benzoate Examples include palladium acid, ruthenium iodide, rhodium bromide, rhodium iodide, rhodium nitrate, rhodium sulfate, rhodium acetate and the like.

Examples of compounds of the above-mentioned metals such as iron, copper, bismuth, cobalt, nickel and tin include halogen compounds such as chloride, bromide, iodide and fluoride of these metals;
Nitrate, sulfate, phosphate, acetate and the like,
Among them, the above-mentioned halogen compounds are particularly preferred.

[0014] As the carrier for supporting the catalyst component, diatomaceous earth, activated carbon, silicon carbide, titania, alumina and the like are preferred, and activated carbon is most preferred. The method of supporting the catalyst component on the support is not required to be a special one, and may be a generally used method, that is, an impregnation method (immersion adsorption method), a kneading method, a deposition method, a coprecipitation method, or the like. It is desirable to prepare by a method or a kneading method. The supported amount of the platinum group metal chloride in the catalyst component supported on the support is:
In terms of metal of platinum group metal, usually 0.1 to 1
0% by weight, particularly preferably 0.5 to 2% by weight. iron,
The supported amount of a compound of a metal such as copper, bismuth, cobalt, nickel, and tin is 1 to 50 gram atomic equivalent, preferably 1 to 10 gram equivalent to the platinum group metal in terms of the amount of these metals.
Preferably, it is a gram atomic equivalent.

In the present invention, the above-mentioned catalyst is used in the form of powder or granules, but the particle size is not particularly limited. , And 4 for granular
A commonly used material having a size of about 200 mesh is preferable.

When at least one compound selected from the group consisting of iron, copper, bismuth, cobalt, nickel and tin is used in combination as the second component, the second component functions as a cocatalyst. By supporting these metal compounds on the carrier in the above amount, the reaction rate between carbon monoxide and nitrite is further improved as compared with the case where the chloride of the platinum group metal is supported alone, and This has the advantage that the deactivation speed of the catalyst is also reduced.

The hydrogen chloride used in the present invention is preferably anhydrous. And in this invention,
The method of causing hydrogen chloride to coexist in the reaction system between the carbon monoxide and the nitrite is not particularly limited. For example, as described in detail below, a method of continuously adding a trace amount of hydrogen chloride, a moving bed It is preferable to use a reactor of the type described above, in which a part of the catalyst is continuously extracted from the packed bed, brought into contact with hydrogen chloride, and then returned to the reactor. It is preferable to select an appropriate method based on the type of reaction between the carbon monoxide and the nitrite, which is adopted from among various types of reaction that can be carried out in the above.

First, a method for continuously adding a small amount of hydrogen chloride will be described. The amount of hydrogen chloride added is usually 1 to 5 per unit time with respect to the platinum group metal in the catalyst component.
0 mol%, preferably 5 to 20 mol%. This addition amount is an appropriate amount to compensate for an amount corresponding to the chlorine content scattered from the catalyst during the reaction between the carbon monoxide and the nitrite. The reaction is inhibited by excessive adsorption of hydrogen, which is not preferable. Specifically, in an actual reaction example, for example, in a fixed bed reactor, gas hourly space velocity (GHSV) is 3000 hr.
^{When the} reaction is carried out at ^-1 , usually 10 to 500 ppm by volume, preferably 20 to 500 ppm in the feed gas (raw material supply gas).
Hydrogen chloride of 100 ppm by volume is added and continuously supplied to the catalyst layer to replenish chlorine scattered from the catalyst.

Next, a method in the case of a reaction in a moving bed system is described. In this method, hydrogen chloride gas is brought into contact with and adsorbed on a catalyst extracted from a catalyst packed bed in a reactor, so that the amount of scattered chlorine is reduced. It is a method of returning to the reactor after replenishment. The method of adsorbing hydrogen chloride on the extracted catalyst may be a generally conceivable method.For example, after filling the extracted catalyst in an appropriate container, it is only necessary to pass hydrogen chloride gas diluted with nitrogen under mild conditions. . In this case, a concentration of hydrogen chloride of 0.1 to 10% by volume is suitable for operation, but is not limited to this.
0% by volume is acceptable. Further, since hydrogen chloride is quickly adsorbed on the catalyst, the time for bringing hydrogen chloride into contact with the extraction catalyst depends on the space velocity (S
Although depending on V), 1 to 30 minutes is sufficient. This contacting operation is preferably carried out at normal temperature and normal pressure, but the range is not limited, of course. For example, the temperature is 0 to 200 ° C. and the pressure is −0.5 to 5 kg /
It can be implemented sufficiently even in the range of cm ² G.

According to the method of the present invention, the catalytic reaction between carbon monoxide and nitrite can be carried out under very mild conditions, which is also a feature of the present invention.
For example, the reaction is carried out at 0-200 ° C., preferably 50-12
It can be performed at a temperature of 0 ° C. and at normal pressure. Of course, it can be carried out without any problem even with a pressurized system, and can be carried out at a pressure of 1 to ²⁰ kg / cm ² G and a temperature of 50 to 150 ° C.

In the present invention, the above-mentioned nitrite as a raw material generates a mixed gas of nitric oxide (NO) and nitrogen dioxide (NO ₂ ) by, for example, decomposition of an aqueous solution of sodium nitrite with nitric acid or sulfuric acid. Then, a part of the NO in the mixed gas is oxidized with molecular oxygen to be changed to nitrogen dioxide (NO ₂ ), and NO _X gas of NO / NO ₂ = 1/1 (volume ratio) is obtained. Is easily synthesized by bringing alcohol into contact with the carbon monoxide, but considering the synthesis up to the nitrite, the contact reaction between the carbon monoxide and the nitrite is 2-3 kg / cm
A slightly pressurized system of the order of ² G is particularly desirable.

The form of the reaction between the carbon monoxide and the nitrite can be either a batch type or a continuous type as long as it is a gas phase, but the continuous type is industrially more advantageous. is there. The catalyst may be present in the reaction system using any of fixed-bed, moving-bed and fluidized-bed reactors.

In the present invention, it is desirable that the raw material gas, carbon monoxide and nitrite, be diluted with an inert gas such as nitrogen gas and then fed to the above-mentioned reactor. Is not particularly limited. However, from the viewpoint of safety, the concentration of the nitrite is usually 20% by volume or less, preferably 5% by volume or less.
20% by volume. Along with that, the concentration of carbon monoxide
The range of 5 to 20% by volume is economically preferable.
That is, considering an industrial production process, it is preferable to circulate and use a gas such as carbon monoxide and nitrite to be used for the reaction, and to purge a part of the circulating gas to the outside of the system. One-pass conversion rate of 20-30
%, The loss increases only if the concentration of carbon monoxide is higher than 20% by volume.
If the capacity is lower than%, there is a problem such as a decrease in productivity. However, ignoring this economy, the concentration of carbon monoxide can actually be up to 80% by volume. That is, the nitrite can be fed in a form diluted with carbon monoxide instead of the inert gas. Therefore, the usage ratio of carbon monoxide to nitrite is usually 0.1 to 10 mol, preferably 0.25 to 1 mol, per mol of nitrite.

[0024] In the present invention, the space velocity of the gas containing the reactor is fed to, carbon monoxide and nitrous acid ester in the range of 500～20000Hr ^-1, preferably in the range of 2000～5000Hr ^-1 It is desirable to perform in. In the production method of this method, the nitrite ester is decomposed to generate nitric oxide (NO) after participating in the reaction, but from the reaction gas derived from the reactor,
It is preferable that this NO is recovered, reacted with oxygen and an alcohol corresponding to the nitrite, converted into a nitrite again, and recycled.

Thus, in addition to the desired product, carbonic acid diester, by-products such as oxalic acid diester, unreacted carbon monoxide and nitrite, nitrogen monoxide, carbon dioxide, inert Although a reaction gas containing a gas or the like is derived, for example, after cooling this reaction gas, uncondensed gas such as carbon monoxide, nitrite, nitric oxide, carbon dioxide, and an inert gas are used as described above. While recirculating to the reactor while purging a part thereof, the diester carbonate is separated and purified from the condensate by a conventional method such as distillation.

As described above, the raw material nitrite is usually prepared by reacting an alcohol and nitrogen oxide in the presence of molecular oxygen as necessary, and the nitrite is contained in the gas. In addition, it contains unreacted alcohol, nitrogen oxides (particularly nitric oxide), and sometimes trace amounts of water and oxygen. In the present invention, good results are obtained even when such a nitrite-containing gas is used as a nitrite source.

In the present invention, by performing the treatment described above, it is possible to prevent a decrease in the activity of the catalyst in the conventional method, and to obtain carbon monoxide in a high yield, a high selectivity and a stable state for a long time. Production of carbonic acid diester by reaction with nitrite can be continued.

[0028]

EXAMPLES Next, the method of the present invention will be described specifically with reference to examples and comparative examples, but these do not limit the method of the present invention at all. The space-time yield (STY) Y (g / L · h) in each of Examples and Comparative Examples was used.
r) is the contact reaction time between carbon monoxide and nitrite, θ (hr), and the amount of carbonic acid diester generated during the reaction is a
(G), and the amount of the catalyst filled in the reaction tube was determined as b (unit: liter (L)) by the following equation. Y = a / (b × θ)

The selectivity X (%) in each of the examples and comparative examples is based on the supplied carbon monoxide, and the carbonic acid diester, oxalic acid diester and carbon dioxide formed at the above θ (hr). , Respectively, a
(Mol), c (mol) and d (mol) were determined by the following equations. X = {a / (a + 2 × c + d)} × 100

Example 1 A catalyst (PdCl ₂ -BiCl ₃ / PdCl ₂ -BiCl ₃ / PdCl ₂ and BiCl ₃ supported on a granular activated carbon in a gas phase reaction tube having an inner diameter of 20 mm (with an outer jacket))
C) After filling 7 mL, fix the reaction tube vertically,
The heat medium is circulated through the jacket of the reaction tube, and the temperature in the catalyst layer becomes 1
The heating was controlled so as to be 00 ° C. From the top 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: 15% by volume, carbon monoxide: 10% by volume, Nitric oxide: 3% by volume, methanol: 6% by volume,
A mixed gas having a composition of 100 ppm by volume of hydrogen chloride and 66% by volume of nitrogen was supplied at a space velocity (GHSV) of 3000 hr ^-1 and reacted under normal pressure. Then
The reaction product passed through the reaction tube was collected by passing through ice-cooled methanol. The obtained collected liquid was analyzed by gas chromatography. Under these conditions,
The reaction was continued for 00 hours, and every 5 hours, the reaction products were sampled and analyzed by gas chromatography as described above.

As a result, the STY of dimethyl carbonate was initially 500 g / L · hr, but dropped to 350 g / L · hr at 10 hours. However, thereafter, 350 g until the end of the reaction 100 hours after the start of the reaction.
/ L · hr. In addition, the selectivity based on carbon monoxide of dimethyl carbonate was 97% at the initial stage, but increased due to an increase in dimethyl oxalate as a by-product.
10 hours after the start of the reaction, the concentration dropped to 92%.
It was almost constant until the end of the reaction (100 hours after the start of the reaction).

Comparative Example 1 Dimethyl carbonate was produced in the same manner as in Example 1 except that no hydrogen chloride was added to the feed gas to the reaction tube. As a result, the STY of dimethyl carbonate was initially 500 g / L · hr, but was changed to 300 g / L · h by 10 hours after the start of the reaction.
・ Hr to 200g / L after 20 hours
Hr, 120 g / Lhr at 30 hours, and 50
At the time, it decreased to 60 g / L · hr. Also,
The selectivity of dimethyl carbonate also gradually decreased with an increase in the amount of dimethyl oxalate produced, and reached 60% at 50 hours.

[Example 2] A catalyst 2 similar to that of Example 1 was placed in a gas-phase reaction tube having an inner diameter of 40 mm (with a bottom extraction tube at the catalyst layer).
00 mL was charged. Separately, a catalyst regeneration tube of the same type was prepared and filled with 200 mL of the same catalyst. Therefore,
The gas-phase reaction tube and the catalyst regeneration tube are fixed vertically, and a mixed gas of a gas containing nitrogen nitrate, oxygen and methyl nitrite synthesized from methanol and carbon monoxide is placed on the gas-phase reaction tube from above. That is, methyl nitrite: 15% by volume, carbon monoxide: 10% by volume, nitric oxide: 3% by volume,
A mixed gas having a composition of methanol: 6% by volume and nitrogen: 66% by volume was subjected to a space velocity of 3000 hr ^-1 (GHS
V) and reacted under normal pressure. From the first hour after the start of the reaction, the catalyst was withdrawn at a rate of 10 mL / hour from the lower part of the catalyst layer of the reaction tube through the lower part withdrawal tube of the catalyst layer, and supplied to the upper part of the catalyst regeneration tube. At the same time, the lower portion of the catalyst regeneration tube met the catalyst layer lower extraction tube of the regeneration tube, and the catalyst was withdrawn at a rate of 10 mL per hour and supplied to the upper portion of the reaction tube. And in the catalyst regeneration tube,
From the first hour after the start of the reaction, a nitrogen gas containing 100 ppm by volume of hydrogen chloride was flowed at a space velocity of 500 hr ^-1 .

After the reaction between methyl nitrite and carbon monoxide as described above, the gas discharged from the reaction tube is collected through ice-cooled methanol and subjected to quantitative analysis by gas chromatography. Was. The reaction was continued for 100 hours under these conditions, and the reaction product was sampled and analyzed by gas chromatography every 5 hours as described above. As a result, the STY of dimethyl carbonate was 500 g / L · hr at the beginning of the reaction, but changed to 370 g / L · h 10 hours after the start of the reaction.
r. However, thereafter, it was almost constant at 350 to 370 g / L · hr until the end of the reaction 100 hours after the start of the reaction. The selectivity based on carbon monoxide of dimethyl carbonate was 97% at the beginning of the reaction,
Due to an increase in dimethyl oxalate as a by-product, the concentration decreased to 93% at 10 hours after the start of the reaction, but thereafter became constant at 90 to 93% until the end of the reaction (100 hours after the start of the reaction).

[0035]

According to the present invention, there is provided a process for producing a carbonic acid diester by contacting nitrite and carbon monoxide in the gas phase in the presence of a solid catalyst in which a catalyst component containing a platinum group metal chloride is supported on a carrier. According to the present invention, hydrogen chloride is supplied to the reaction system in an amount necessary for compensating for the amount of chlorine scattered from the chloride of the platinum group metal during the reaction. Since the decrease in the catalytic activity is significantly suppressed, the carbonic diester can be industrially advantageously obtained.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C07C 69/96 B01J 27/13 C07C 68/00 C07B 61/00 301 CA (STN) WPI / L (QUESTEL)

Claims (10)

(57) [Claims] 1. A diester carbonate comprising reacting a nitrite and carbon monoxide in the gas phase in the presence of a solid catalyst having a catalyst component containing a platinum group metal chloride supported on a carrier. A method for producing a carbonic acid diester, which comprises supplying an amount of hydrogen chloride necessary for compensating for chlorine scattered from a platinum group metal chloride during the reaction to the reaction system. 2. The method for producing a carbonic acid diester according to claim 1, wherein the chloride of the platinum group metal is palladium chloride. 3. The amount of the platinum group metal chloride carried on the carrier is 0.1 to 1 in terms of the platinum group metal metal.
The method for producing a carbonic acid diester according to claim 1, which is 0% by weight. 4. The process for producing a carbonic acid diester according to claim 1, wherein hydrogen chloride is supplied in an amount of 1 to 50 mol% per unit time with respect to the platinum group metal chloride. 5. The process for producing a diester carbonate according to claim 1, wherein 10 to 500 ppm by volume of hydrogen chloride is added to a raw material gas containing a nitrite and carbon monoxide and supplied to the reaction system. 6. A diester carbonate comprising reacting a nitrite and carbon monoxide in the gas phase in the presence of a solid catalyst having a catalyst component containing a platinum group metal chloride supported on a carrier. In carrying out the production method, an amount of hydrogen chloride necessary for compensating for the amount of chlorine scattered from the chloride of the platinum group metal during the reaction is supplied to the reaction system. A method for suppressing a decrease in activity of a catalyst component containing chloride. 7. A reduced activity inhibiting a catalyst component according to claim 6 chlorides of the platinum group metal is palladium chloride. 8. The amount of the platinum group metal chloride supported on the carrier is 0.1 to 1 in terms of the platinum group metal metal relative to the carrier.
0 deactivators suppress <br/> system a catalyst component according to claim 6 by weight. 9. The hydrogen chloride, platinum group activity lowering suppression method of the catalyst component of claim 6 unit time per 1 to 50 mol% supplied to metal chlorides. 10. The activity of the catalyst component according to claim 6, wherein 10 to 500 ppm by volume of hydrogen chloride is added to a raw material gas containing a nitrite and carbon monoxide and supplied to the reaction system.
How to control drop.