JP3201057B2 - Process for producing glycolic acid ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing a glycolic acid ester with high selectivity and high yield by reacting oxalic acid diester with hydrogen in a gas phase using a novel solid catalyst. About. Glycolic acid esters are very useful as detergents for boilers, plating additives, etching agents, tanning agents, and as intermediates for the production of detergent builders and biodegradable polymers. It is a useful compound.

[0002]

2. Description of the Related Art As a method for producing a glycolic acid ester, as disclosed in Japanese Patent Publication No. 55-42971, U.S. Pat. No. 4,112,245, and German Patent No. 459,603, carbonates are disclosed. A method is known in which an oxalic acid diester such as diethyl oxalate is contacted with hydrogen in the presence of a catalyst obtained from cupric acid and chromic acid. However, in these methods, since this reaction is a sequential reaction, unless the catalyst is improved or the reaction conditions are not optimized, the hydrogenation reaction further proceeds and ethylene glycol is produced as a by-product, resulting in glycosylation. However, the selectivity of the -ester was lowered, and the separation and purification of the glycolate was complicated.

[0003] In these methods, since a copper chromium-based catalyst is used as a catalyst, it is necessary to recover chromium from a spent catalyst after use. It was extremely difficult to prevent chrome from entraining wastewater and the like. Therefore, from the viewpoint of environmental hygiene, development of a production method that does not use extremely toxic chromium has been desired.

[0004] In order to solve the above problems, for example, Japanese Patent Application Laid-Open No. 55-40685 discloses that oxalic acid diester is prepared by changing the reaction conditions in the presence of a catalyst selected from ruthenium, nickel and Raney-nickel. A reaction product containing a relatively large amount of either ethylene glycol or a glycolic acid ester is obtained by performing a catalytic reaction between the glycolic acid and hydrogen, but the glycolic acid ester is industrially produced. For this purpose, it is necessary to further increase the reaction rate to improve the selectivity and to carry out the reaction under mild reaction conditions using an inexpensive catalyst. In addition, Japanese Patent Publication No. 60-4
No. 5938 discloses a method in which a similar catalytic reaction is carried out using a catalyst in which a copper ammine complex is supported on a silica carrier, and Japanese Patent Publication No. 62-37030 using a catalyst in which silver or palladium is supported. However, these catalysts had low activity and low selectivity for glycolic acid esters, and were not sufficient for industrial use.

[0005]

In the known method for producing a glycolic acid ester, as described above, the hydrogenation reaction of oxalic acid diester is a sequential reaction, and when the reaction proceeds further, ethylene glycol is formed. When such a side reaction occurs, there is a problem that the selectivity of the glycolic acid ester is lowered. An object of the present invention is to carry out a hydrogenation reaction of oxalic acid diester with hydrogen under mild reaction conditions in the presence of a novel solid catalyst by a gas phase method in which the reaction product can be easily separated and recovered, and the glyco- It is an object of the present invention to provide an industrially suitable method for producing a glycolic acid ester which can produce a luic acid ester with a high selectivity and a high yield.

[0006]

SUMMARY OF THE INVENTION In order to overcome the above-mentioned problems in the known method for producing a glycolic acid ester, the present inventors have proposed a gas phase catalytic reaction between oxalic acid diester and hydrogen. As a result of intensive studies, it has been found that when the gas phase catalytic reaction of oxalic acid diester and hydrogen is carried out in the presence of a novel hydrogenation catalyst, the desired product, glycolic acid ester, can be obtained with extremely high activity and selectivity. The inventors have found the present invention.

That is, the present invention relates to a method for producing a glycolic acid ester by subjecting an oxalic acid diester to hydrogenation reaction with hydrogen in the gas phase, the method comprising the general formula (COOR) ₂ (where R is a carbon atom Represents 1 to 6 lower alkyl groups)
In the presence of a solid catalyst in which at least copper metal and silver metal are supported on a carrier,
The present invention relates to a process for producing a glycolic acid ester, comprising synthesizing a glycolic acid ester by performing a hydrogenation reaction in the gas phase with hydrogen.

Hereinafter, the method of the present invention will be described in detail. As the oxalic acid diester used in the present invention, a diester of oxalic acid and a lower aliphatic monohydric alcohol having 1 to 6 carbon atoms is preferably used. Specifically, dimethyl oxalate, diethyl oxalate, dipropyl oxalate, dibutyl oxalate, diamyl oxalate, and the like can be preferably mentioned. In particular, the lower aliphatic monovalent alcohol having 1 to 4 carbon atoms is preferably used. Oxalic acid diesters of thiol are preferred, with dimethyl oxalate and diethyl oxalate being most preferred.

The catalyst used in the present invention is a solid catalyst in which at least copper metal and silver metal are supported on a carrier such as silica, alumina, titania, zirconia, diatomaceous earth, zinc oxide, lanthanum oxide and activated carbon. Further, in addition to the copper metal and the silver metal, a solid catalyst supporting a copper compound and / or a silver compound may be used.
The loading amount of copper metal and silver metal is preferably 5 to 50% by weight, particularly preferably 5 to 30% by weight, and preferably silver is preferably 0 to 30% by weight in terms of metal relative to the carrier. 0.01 to 20% by weight, particularly preferably 0.02 to 20% by weight.
It is desirably 10% by weight.

The above-mentioned carrier may be in the form of powder, granules,
Alternatively, a molded body is used, but the size thereof is not particularly limited. In the case of a powder, the size is usually 20 to 100 μm, and in the case of a granular material, it is 4 to 2 μm.
Those having a size of about 00 mesh and those of several mm in the case of a molded body are suitably used.

The solid catalyst used in the hydrogenation reaction of the present invention is prepared by preparing an aqueous solution of a copper compound and a silver compound in which a water-soluble compound such as copper, silver sulfate, nitrate, chloride and complex salt is dissolved. The catalyst is prepared by adding the above-mentioned carrier to the carrier and supporting the catalyst component on the carrier by an appropriate method, and then reducing the copper compound and the silver compound carried on the carrier with hydrogen gas or the like.

The method of supporting the catalyst component on the carrier does not need to be special, and is usually carried out, that is,
Impregnation method (immersion adsorption method), kneading method, deposition method, evaporation to dryness method,
A coprecipitation method or the like may be used, but a coprecipitation method, an impregnation method or an evaporation to dryness method is preferable because of simplicity. The catalyst component is supported, for example, by gradually adding an alkalizing agent such as sodium hydroxide, sodium carbonate, ammonium carbonate, potassium hydroxide, aqueous ammonia to an aqueous solution of a copper compound and a silver compound in which the above carrier is suspended. The precipitation is performed by depositing a precipitate containing a copper compound and a silver compound on a carrier, and separating a precipitate in which the copper compound and the silver compound are carried on the carrier by filtration or concentration. The loading of the catalyst component on the carrier may be performed simultaneously or sequentially.

The supported catalyst component is reduced by thoroughly washing the above-mentioned precipitate with water, drying it in air at a temperature of, for example, about 120 ° C., and then using a general reducing agent such as hydrogen gas or hydrazine. In the reduction treatment using hydrogen gas, prior to the hydrogenation reaction of oxalic acid diester,
It is preferable to carry out a reduction treatment with a general hydrogen gas at a temperature of 150 to 400 ° C. for a reduction time of 1 to 2 hours to produce a solid catalyst in which copper metal and silver metal are mainly supported.

In the solid catalyst after the above-mentioned reduction treatment, the copper compound and / or the silver compound which were not sufficiently reduced together with the copper metal and the silver metal have a small ratio (the amount of the copper compound and / or the silver metal supported on the carrier). The oxalic acid diester of the present invention is supported even when the oxalic acid diester of the present invention is supported at a ratio of 20% by weight or less, particularly 10% by weight or less in the residual ratio represented by the ratio of the total amount of the copper compound and the silver compound to the total amount of the metal and the metal compound component. There is no hindrance to the hydrogenation reaction, and it can be used as it is as a hydrogenation catalyst. Further, in the solid catalyst of the present invention, a metal or metal compound other than copper metal and silver metal may be supported as a catalyst component together with copper metal and silver metal.

[0015] The solid catalyst prepared by the above-described method and supporting at least copper metal and silver metal has a high level of activity (eg, space-time yield: STY) of the hydrogenation reaction and is continuously maintained. Since the catalyst has high mechanical strength and does not collapse, it can be used stably for a long period of time, and is a catalyst suitable for the hydrogenation reaction of oxalic acid diester of the present invention.

In the present invention, the contact reaction between oxalic acid diester and hydrogen is carried out at a reaction temperature of 100 to 300 ° C., preferably 100 to 250 ° C., and a reaction pressure of normal pressure to about 30 kg / cm ^2. It can be carried out under the following conditions.
Further, the molar ratio of hydrogen and oxalic acid diester (hydrogen / oxalic acid diester) introduced into the reaction tube filled with the solid catalyst is preferably 2 to 100, particularly preferably 4 to 50. The contact time is preferably about 0.01 to 20 seconds, particularly about 0.2 to 8 seconds.

In the present invention, hydrogen and oxalic acid diester of the raw material gas are diluted with a lower alcohol vapor such as methanol or ethanol or an inert gas such as nitrogen gas and fed to the above-mentioned solid catalyst for hydrogenation. It is desirable to be done. Although the composition is not particularly limited from the viewpoint of the reaction, for example, oxalic acid diester is obtained by evaporating an alcohol solution of oxalic acid diester having a concentration of 10 to 40% by weight, particularly 15 to 35% by weight. It is preferable that the hydrogen gas is supplied onto the solid catalyst together with the hydrogen gas. In this case, it is preferable to use an alcohol having the same alkyl group as the alkoxy group of the oxalic acid diester.

[0018]

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 in any way. In addition, of the reaction conditions in each of the examples and comparative examples, the liquid hourly space velocity: LHSV
(G / ml · hr), space velocity: SV (hr ⁻¹ ), and contact time: CT (sec) were determined by the following equations.

[0019]

(Equation 1)

[0020]

(Equation 2)

[0021]

(Equation 3)

In each of Examples and Comparative Examples, the conversion of oxalic acid diester (%), the selectivity of glycolic acid ester (%), the selectivity of ethylene glycol (%), and the STY of methyl glycolate were determined. Was determined by the following equation.

[0023]

(Equation 4)

[0024]

(Equation 5)

[0025]

(Equation 6)

[0026]

(Equation 7)

Examples 1 to 4 [Preparation of catalyst] Copper nitrate (Cu (NO ₃ ) ₂ .3H ₂ O)
39.2 g and 2.1 g of silver nitrate (AgNO ₃ ) were added to 200 parts of water.
and dissolved in a commercially available silica sol (catalyst chemical:
(Cataloid S30L) was added and stirred.
To this solution, 14.4 g of ammonium carbonate was previously added with 85 of water.
The solution dissolved in ml was slowly dropped over 30 minutes while stirring. After completion of the dropwise addition, the reaction product was aged for 1.5 hours while stirring, and the formed precipitate was separated by filtration. The separated precipitate is washed with about 500 ml of water and filtered for 3 times.
Repeated times. Take out the obtained bluish white cake,
After drying at 40 ° C. for 12 hours, a support (a precursor of a solid catalyst) in which a copper compound and a silver compound are supported on a support is formed. The support is further dried at 350 ° C. for 2 hours in a stream of hydrogen.
After a time reduction treatment, a solid catalyst carrying copper metal and silver metal (average particle diameter: 1 to 2 mm) was prepared.

[Synthesis of Methyl Glycolate] 20 ml of the solid catalyst obtained above was used to prepare an inner diameter of 20 mm and a length of 700 m.
After filling into a glass gas-phase reaction tube of m, the reaction tube was vertically installed in an electric furnace, and the temperature in the catalyst layer was controlled so that the reaction temperature was as shown in Table 1. From the top of these reaction tubes, the liquid hourly space velocity (LHS
V), space velocity (SV) and contact time (CT) such that the molar ratio of hydrogen to dimethyl oxalate is 12.0 to 12.3, and a solution of hydrogen and dimethyl oxalate and methanol (25 (% Methanol solution of dimethyl oxalate by weight) was supplied to the reaction system while the hydrogenation reaction of dimethyl oxalate was carried out at the reaction temperature under normal pressure, and the reaction product passed through the reaction tube was cooled with ice. Collected in trap.
The conversion of dimethyl oxalate, the selectivity of glycolic acid ester and the space-time yield (STY), and the selectivity of ethylene glycol were determined from the results of analyzing the obtained collected liquid by gas chromatography, and the results are shown in Table 1. Indicated.

Comparative Example 1 [Preparation of Catalyst] A catalyst in which a copper ammine complex was supported on a silica carrier was prepared in the same manner as in Examples 8 to 11 described in JP-B-60-45938. Copper nitrate (Cu (NO
The _{3) 2 · 3H 2 O)} 38.0g was dissolved in water 200 ml, the pH about by adding concentrated aqueous ammonia 60ml to 1
As Nos. 1 to 12, deep blue solutions containing a copper ammine complex were obtained. 66.6 g of 30% by weight colloidal silica sol was added to this deep blue solution and stirred at room temperature for several hours, then the temperature was raised to evaporate most of the water.
Dried for hours. Then, the dried product is thoroughly washed with water, dried in air at 140 ° C. for 14 hours, and then dried in a stream of hydrogen for 35 hours.
A reduction treatment was performed at 0 ° C. for 2 hours to prepare a solid catalyst.

[Synthesis of methyl glycolate] Using 10 ml of the solid catalyst obtained above, the liquid hourly space velocity (LHSV), the hourly space velocity (SV) and the contact time (C
In T), hydrogen and a solution of dimethyl oxalate and methanol (25% by weight of dimethyl oxalate in methanol) are supplied to the reaction system such that the molar ratio of hydrogen to dimethyl oxalate becomes 25.0. At a reaction temperature of 220 ° C.,
The hydrogenation reaction of dimethyl oxalate was performed in the same manner as in Example 1 under normal pressure. Table 1 shows the obtained results.

Comparative Example 2 [Preparation of Catalyst] A catalyst having silver supported on a silica carrier was prepared in the same manner as in Example 1 described in JP-B-62-37030. 5 g of silver nitrate (AgNO ₃ ) was dissolved in 20 ml of water, and 145 g of 33% colloidal silica was added thereto. An aqueous solution of sodium hydroxide (a solution of 1.24 g of NaOH in 100 ml of water) was gradually added to the silica suspension, and after completion of the addition, the mixture was aged for 1 hour, and the resulting precipitate was collected by filtration. Filtrated, substantially AgOH-
The SiO ₂ solid was washed twice with water and then dried at 140 ° C. overnight to form a support. After adding 40 ml of a 3% hydrazine aqueous solution to 2 g of the thus obtained support and leaving the mixture to stand overnight, the solid matter was collected by filtration, washed with water, dried at room temperature under vacuum, and then further dried at 150 to 20 ml.
The catalyst was prepared by drying at 0 ° C.

[Synthesis of methyl glycolate] Using 10 ml of the solid catalyst obtained above, the liquid hourly space velocity (LHSV), the hourly space velocity (SV) and the contact time (C
In T), hydrogen and a solution of dimethyl oxalate and methanol (25% by weight of dimethyl oxalate in methanol) are supplied to the reaction system such that the molar ratio of hydrogen to dimethyl oxalate becomes 25.0. At a reaction temperature of 249 ° C.,
The hydrogenation reaction of dimethyl oxalate was performed in the same manner as in Example 1 under normal pressure. Table 1 shows the obtained results.

Example 5 [Preparation of catalyst] Copper nitrate (Cu (NO ₃ ) ₂ .3H ₂ O)
19 g and 2.3 g of silver nitrate (AgNO ₃ ) in 200 m of water
and heated to 75-80 ° C., and a commercially available silica sol (Cataloid S30L, manufactured by Catalyst Chemicals Co., Ltd.)
5 g was added and stirred. A solution in which 7 g of sodium hydroxide was previously dissolved in 200 ml of water was slowly added dropwise to this solution with stirring for 30 minutes. After completion of the dropwise addition, the reaction product was aged for 2 hours while stirring, and the generated precipitate was separated by filtration. The separated precipitate is about 500 ml of water,
Washing and filtration were repeated twice. The obtained cake is taken out and dried at 140 ° C. for 12 hours to form a support (a precursor of a solid catalyst) in which a copper compound and a silver compound are supported on a support. 35 in a stream of hydrogen
A reduction treatment was performed at 0 ° C. for 2 hours to prepare a solid catalyst (average particle diameter: 1 to 2 mm) supporting copper metal and silver metal.

[Synthesis of methyl glycolate] Using 10 ml of the solid catalyst obtained above, the liquid space velocity (LHSV), space velocity (SV) and contact time (C
In T), hydrogen and a solution of dimethyl oxalate and methanol (25% by weight of dimethyl oxalate in methanol) are supplied to the reaction system such that the molar ratio of hydrogen to dimethyl oxalate becomes 22.1. While the reaction temperature is 237 ° C,
The hydrogenation reaction of dimethyl oxalate was performed in the same manner as in Example 1 under normal pressure. Table 1 shows the obtained results.

Example 6 [Preparation of catalyst] Copper nitrate (Cu (NO ₃ ) ₂ .3H ₂ O)
19 g and 2.1 g of silver nitrate (AgNO ₃ ) in 200 m of water
Then, after adding 60 ml of 25% by weight ammonia water, 66.5 g of a commercially available silica sol (Cataloid S30L, manufactured by Catalyst Chemicals Co., Ltd.) was added thereto, followed by stirring. After the reaction was aged for 1 hour while stirring the solution,
The mixture was concentrated in a warm bath at ℃ C, and the resulting precipitate was washed with about 200 ml of water four times and filtered. The cake obtained is taken out and 12
After drying at 0 ° C. for 12 hours and further firing at 500 ° C. for 3 hours to form a support (a precursor of a solid catalyst) in which a copper compound and a silver compound are supported on a support, the support is hydrogenated. In a gas stream, reduction treatment was performed at 350 ° C. for 2 hours to prepare a solid catalyst (average particle diameter: 1 to 2 mm) supporting copper metal and silver metal.

[Synthesis of methyl glycolate] Using 10 ml of the solid catalyst obtained above, the liquid space velocity (LHSV), space velocity (SV) and contact time (C
In T), hydrogen and a solution of dimethyl oxalate and methanol (25% by weight of dimethyl oxalate in methanol) are supplied to the reaction system so that the molar ratio of hydrogen to dimethyl oxalate becomes 5.65. Meanwhile, at a reaction temperature of 225 ° C,
The hydrogenation reaction of dimethyl oxalate was performed in the same manner as in Example 1 under normal pressure. Table 1 shows the obtained results.

Example 7 [Preparation of catalyst] Silver nitrate (AgNO ₃ ) in Example 5
Example 5 except that the amount of used was 0.0633 g.
A catalyst was prepared in the same manner as described above. The catalyst supported about 20% by weight of copper and about 0.16% by weight of silver.

[Synthesis of methyl glycolate] Using 20 ml of the solid catalyst obtained above, the liquid hourly space velocity (LHSV), the hourly space velocity (SV) and the contact time (C
In T), hydrogen and a solution of dimethyl oxalate and methanol (25% by weight of dimethyl oxalate in methanol) are supplied to the reaction system so that the molar ratio of hydrogen to dimethyl oxalate becomes 12.3. At a reaction temperature of 230 ° C.,
The hydrogenation reaction of dimethyl oxalate was performed in the same manner as in Example 1 under normal pressure. Table 1 shows the obtained results.

Example 8 [Synthesis of Ethyl Glycolate] Using 20 ml of the catalyst prepared in the same manner as in Example 1, the dimethyl oxalate in Example 1 was changed to diethyl oxalate, and the liquid space shown in Table 1 was used. At a velocity (LHSV), space velocity (SV) and contact time (CT), the molar ratio of hydrogen to diethyl oxalate is 12.
While supplying hydrogen and a solution of diethyl oxalate and ethanol (ethanol solution of 25% by weight of diethyl oxalate) to the reaction system so as to be 0, the reaction temperature was 220 ° C.
In Example 1, the hydrogenation reaction of diethyl oxalate under normal pressure was performed.
The same was done. Table 1 shows the obtained results.

Example 9 [Synthesis of Butyl Glycolate] Using 20 ml of the catalyst prepared in the same manner as in Example 1, dimethyl oxalate in Example 1 was changed to dibutyl oxalate, and the liquid space shown in Table 1 was used. At a velocity (LHSV), space velocity (SV) and contact time (CT), the molar ratio of hydrogen to dibutyl oxalate is 12.
While supplying hydrogen and a solution of dibutyl oxalate and butanol (25% by weight of dibutyl oxalate in butanol) to the reaction system, the reaction temperature was set to 220 ° C.
In Example 1, the hydrogenation reaction of dibutyl oxalate under normal pressure was performed.
The same was done. Table 1 shows the obtained results.

Example 10 [Synthesis of methyl glycolate] Using 20 ml of the catalyst prepared in the same manner as in Example 1, the liquid hourly space velocity (LH
SV), space velocity (SV) and contact time (CT)
While supplying hydrogen, nitrogen, and dimethyl oxalate (dimethyl oxalate containing no methanol) to the reaction system so that the molar ratio of hydrogen to dimethyl oxalate becomes 12.0, at a reaction temperature of 216 ° C, The hydrogenation reaction of dimethyl oxalate was performed in the same manner as in Example 1 under normal pressure. Table 2 shows the obtained results.

Comparative Example 3 [Synthesis of methyl glycolate] Using 10 ml of the catalyst prepared in the same manner as in Comparative Example 1, the liquid hourly space velocity (LH
SV), space velocity (SV) and contact time (CT)
While supplying hydrogen, nitrogen, and dimethyl oxalate (dimethyl oxalate containing no methanol) to the reaction system so that the molar ratio of hydrogen to dimethyl oxalate becomes 25.0, at a reaction temperature of 220 ° C, The hydrogenation reaction of dimethyl oxalate was performed in the same manner as in Example 1 under normal pressure. Table 2 shows the obtained results.

Comparative Example 4 [Synthesis of methyl glycolate] Using 10 ml of the catalyst prepared in the same manner as in Comparative Example 2, the liquid hourly space velocity (LH
SV), space velocity (SV) and contact time (CT)
While supplying hydrogen, nitrogen, and a dimethyl oxalate solution (a solution of dimethyl oxalate only without methanol) to the reaction system so that the molar ratio of hydrogen to dimethyl oxalate becomes 25.0, the reaction temperature is increased. A hydrogenation reaction of dimethyl oxalate was carried out at 249 ° C. under normal pressure in the same manner as in Example 1. Table 2 shows the obtained results.

[0044]

[Table 1]

[0045]

[Table 2]

[0046]

According to the method of the present invention using the novel solid catalyst "a solid catalyst in which at least copper metal and silver metal are supported on a carrier", the by-product of ethylene glycol and the desired production by sequential reaction are obtained. It solves the problems of the conventionally known method for producing a glycolic acid ester, such as a decrease in the selectivity of a glycolic acid ester as a product, and facilitates separation and recovery of a reaction product under mild reaction conditions. By performing a hydrogenation reaction of oxalic acid diester with hydrogen by a simple gas phase method, a glycolic acid ester can be produced with high selectivity and high yield.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-180432 (JP, A) JP-A-57-123143 (JP, A) JP-A-57-122938 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C07C 69/675 C07C 67/31 C07C 27/04 CA (STN) CASREAT (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. A method for producing a glycolic acid ester by subjecting an oxalic acid diester to hydrogenation reaction with hydrogen in the gas phase, wherein a compound represented by the general formula (COOR) ₂ (wherein R represents 1 to 6 carbon atoms). Oxalic acid diester represented by a lower alkyl group) is subjected to hydrogenation reaction in the gas phase with hydrogen in the presence of a solid catalyst in which at least copper metal and silver metal are supported on a carrier to form a glycolic acid ester. A method for producing a glycolic acid ester, which is characterized by being synthesized.