JP3129547B2 - Method for producing glycolate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a glycolic acid salt useful as a synthetic intermediate, a chelating agent, a raw material for a surfactant, a raw material for a high molecular compound such as polyester, and the like.

[0002]

2. Description of the Related Art As a method for producing glycolic acid, conventionally,
A method for producing from formaldehyde, carbon monoxide and water in the presence of an acidic catalyst is known. This production method is a method under severe reaction conditions of high temperature and high pressure (U.S. Pat. No. 2,153,064), and has problems such as expensive production equipment. Also, in JP-A-61-277649,
It is described that glyoxal obtained by oxidizing ethylene glycol and water are reacted in the presence of an inorganic acid salt such as aluminum nitrate to obtain glycolic acid.
There are problems such as the need to remove the catalyst and manufacture glyoxal. As a method for producing glycolate by direct oxidative dehydrogenation using ethylene glycol as a starting material, U.S. Pat. No. 2,384,817 describes that a cadmium compound is effective as a catalyst for producing a carboxylate in the presence of an alkali. Although it is shown that glycolate and oxalate are produced from ethylene glycol, specific reaction conditions, selectivity, etc. are unknown, and the use of a highly toxic cadmium compound poses an industrial problem. is there. JP-A-50-93923 describes a diethylene glycol dehydrogenation method in which diethylene glycol is dehydrogenated with a caustic alkali in the liquid phase and reacted in the presence of a copper and / or nickel-containing catalyst. There is no description of the yield. JP-A-61-18
No. 9247 describes a method for producing an oxydicarboxylate by reacting polyethylene glycol in the presence of a catalyst containing an alkali metal or alkaline earth metal hydroxide, water, and a copper and zirconium compound. There is no description of the production and yield of glycolate.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to use inexpensive monoethylene glycol as a starting material, reduce by-products, achieve high conversion, high selectivity, and use a catalyst many times. An object of the present invention is to provide a method for producing a glycolate which can be used repeatedly and is economically advantageous.

[0004]

The present inventors have conducted various studies on a method for obtaining glycolate by oxidative dehydrogenation of monoethylene glycol, and as a result, have found that water and copper or a catalyst containing copper and zirconium coexist. It has been found that glycolate is selectively formed by adding a specific amount of an alkali metal hydroxide, and as a result of further intensive studies, the present invention has been completed. That is, the present invention relates to monoethylene glycol in an amount of 0.1 to 0.1 with respect to monoethylene glycol which is subjected to a reaction with an alkali metal hydroxide in the presence of water and a catalyst containing copper or copper and zirconium.
This is a method for producing a glycolic acid salt, which is characterized in that it is oxidatively dehydrogenated by adding 8- to 1.3-fold mol.

The glycolate produced by oxidative dehydrogenation of the monoethylene glycol of the present invention is produced as an alkali metal salt of glycolic acid.

As the alkali metal hydroxide used in the present invention, sodium hydroxide, potassium hydroxide and the like are particularly preferably used. These can be used in the form of flakes, powders, pellets, etc. and their aqueous solutions, but are easy to handle in aqueous solutions.

In the present invention, the amount of the alkali metal hydroxide used is an important factor and affects the yield of the product. The amount of the alkali metal hydroxide used is 0.8 to 1.3 times the mol of the monoethylene glycol used for the reaction,
Particularly preferably, it is in the range of 0.9 to 1.1 times the molar amount. When the amount of the alkali metal hydroxide used is less than this range, the reaction conversion of monoethylene glycol as a raw material decreases, and the yield of glycolate decreases. On the other hand, when the amount of the alkali metal hydroxide used is larger than this range, by-products such as dicarboxylates are promoted, and the yield of glycolate decreases.

[0008] The present invention can be carried out in the presence of water.
By using water, monoethylene glycol and alkali metal hydroxide can be reacted in a homogeneous system, and as a result, glycolate can be obtained in high yield. The amount of water used in the reaction is at least 10% by weight, preferably in the range of 50 to 500% by weight, based on monoethylene glycol.

The catalyst used in the present invention contains copper or copper and zirconium as essential components.

The catalyst containing copper used in the present invention is used as a metal or a copper compound. As a raw material of copper, for example, metal copper, nitrate, sulfate, carbonate, oxide,
Inorganic substances such as halides and hydroxides can be used. Further, any of organic salts such as formate, acetate, propionate and lactate can be used. The form of the catalyst is not particularly limited. For example, a catalyst obtained by oxidizing a metal copper surface and reducing it with hydrogen, a catalyst obtained by developing Raney copper with an aqueous alkali solution, an activity obtained by thermally decomposing and / or reducing copper formate, copper carbonate and the like. Copper oxide can be used as it is or by being impregnated in an alkali-resistant carrier or electrolessly plated and carried. Examples of preferred carriers include titanium oxide, zirconium oxide, silicon carbide and the like. In particular, developed Raney copper and a copper catalyst supported on zirconium oxide by a coprecipitation method or an impregnation method are preferably used in view of activity to the reaction and life of the catalyst.

The catalyst containing copper and zirconium used in the present invention is used as a metal or a metal compound. As the raw material, for example, inorganic substances such as copper metal, nitrate, sulfate, carbonate, oxide, halide, and hydroxide can be used. Further, any of organic salts such as formate, acetate, propionate and lactate can be used. The form of the catalyst is not particularly limited. For example, an aqueous solution of an alkali metal hydroxide is added to a solution in which a copper compound and a zirconium compound are dissolved in water to precipitate a hydroxide, and the precipitate is washed with water, dried, oxidized in air or oxygen, Catalysts containing copper and zirconium that have been reduced in a hydrogen atmosphere are preferred. Further, copper and zirconium can be used by being supported on a carrier. Examples of preferred carriers include titanium oxide, zirconium oxide, silicon carbide and the like.

The content of copper in the catalyst containing copper and zirconium is 3 to 50% by weight, preferably 5 to 35% by weight, based on the total amount of copper and zirconium.

The reaction can be carried out in any of batch, semi-batch and continuous reaction modes. When the reaction is carried out by a batch reaction, the amount of the catalyst used is 5 to 50% by weight, preferably 10 to 30% by weight, based on monoethylene glycol. When the reaction is carried out by a continuous reaction such as in a fixed bed, the reaction is carried out at a liquid hourly space velocity (LHSV) (supply volume velocity of the reaction liquid per reaction layer volume) of 0.05 to 20 hr ^-1 .

The reaction is carried out at a temperature of 220 ° C. or lower, usually 120 to 210 ° C., preferably 140 to 200 ° C. in order to prevent decarboxylation and hydrogenolysis of monoethylene glycol and the formed glycolate. .

Since the reaction is an oxidative dehydrogenation reaction and involves the generation of hydrogen, it is preferable to reduce the reaction pressure as much as possible from the viewpoint of the reaction rate. Usually, the pressure is not lower than the minimum pressure for proceeding the reaction in the liquid phase, preferably within the range of 5 to 50 kg / cm ² G.

The catalyst is separated and removed from the reaction mixture after the reaction according to the method of the present invention to obtain the desired aqueous solution of glycolate. The solution can be appropriately purified as necessary to obtain high-quality glycolate and free glycolic acid as products. On the other hand, the catalyst separated by filtration or sedimentation can be recovered and reused for the next reaction as it is. Of course, the recovered catalyst may be subjected to a regeneration treatment as needed and used.

[0017]

According to the method of the present invention, glycolate can be produced from monoethylene glycol, which is an inexpensive raw material, at a high yield and a high selectivity under relatively mild reaction conditions. In addition, even when the catalyst is recovered and used repeatedly or continuously, the activity and selectivity of the catalyst do not decrease much, the catalyst life is long, and as a result, the process can be simplified, and the catalyst cost and equipment cost can be reduced. Quality products can be supplied at low cost.

[0018]

The present invention will be described below in detail with reference to examples. However, the present invention is not limited by these examples.

Here, the conversion of monoethylene glycol and the yield of glycolate are derived from the following equations.

Conversion of monoethylene glycol (%) =
Number of moles of reacted monoethylene glycol / Number of moles of monoethylene glycol used for reaction × 100 Yield of glycolate (%) = Number of moles of glycolate produced / Number of moles of monoethylene glycol used for reaction × 100 Example 1 62 g (1.0 mol) of monoethylene glycol, 42 g (1.05 mol) of sodium hydroxide, 165 g of water, and 12.4 g of developed Raney copper were charged into an autoclave having an internal volume of 500 ml, and hydrogen gas was used three times. After the internal substitution, the reaction was carried out at a reaction temperature of 150 ° C. and a reaction pressure of 10 kg / cm ² G until no more hydrogen was generated. The time required for the reaction is 15
It was 5 hours after the temperature was raised to 0 ° C. After completion of the reaction, the reaction solution was withdrawn and analyzed. The conversion of monoethylene glycol was 97.2%, and the yield of sodium glycolate was 9%.
It was 4.1%, and the yield of by-produced sodium oxalate was 2.5%.

Example 2 An aqueous solution of sodium hydroxide was added to a solution of 38.4 g of zirconium oxychloride and 6.2 g of copper nitrate in 300 ml of water to precipitate a hydroxide, and the precipitate was washed with water and dried. Heat treatment was performed at 500 ° C. for 3 hours, and further reduction treatment was performed at 230 ° C. for 6 hours in a hydrogen stream to prepare a copper- and zirconium-containing catalyst.

The reaction was carried out under the same conditions as in Example 1 except that 8 g of the copper- and zirconium-containing catalyst was used instead of the developed Raney copper. The time required for the reaction was 8 hours after the temperature was raised to 150 ° C. After completion of the reaction, the reaction solution was withdrawn and analyzed. The conversion of monoethylene glycol was 98.0%, the yield of sodium glycolate was 92.6%, and the yield of sodium oxalate was 3.6%. there were.

COMPARATIVE EXAMPLE 1 62 g (1.0 mol) of monoethylene glycol, 60 g (1.5 mol) of sodium hydroxide, 165 g of water, and 12.4 g of developed Raney copper were charged into an autoclave having an internal volume of 500 ml. After the internal replacement, the reaction temperature 1
The reaction was carried out at 50 ° C. and a reaction pressure of 10 kg / cm ² G until hydrogen generation ceased. The time required for the reaction was 150
7 hours after the temperature was raised to ° C. After completion of the reaction, the reaction solution was extracted and analyzed. As a result, the conversion of monoethylene glycol was 98.5% and the yield of sodium glycolate was 45.
7%, and the yield of sodium oxalate by-produced was 5%.
0.6%.

COMPARATIVE EXAMPLE 2 62 g (1.0 mol) of monoethylene glycol, 16 g (0.4 mol) of sodium hydroxide, 165 g of water, and 12.4 g of developed Raney copper were charged into an autoclave having an internal volume of 500 ml. After the internal replacement, the reaction temperature 1
The reaction was carried out at 50 ° C. and a reaction pressure of 10 Kg / cm ² G until no more hydrogen was generated. The time required for the reaction was 150
4 hours after the temperature was raised to ° C. After completion of the reaction, the reaction solution was extracted and analyzed. As a result, the conversion of monoethylene glycol was 34.5%, and the yield of sodium glycolate was 31.
6%, and the yield of by-produced sodium oxalate was 1.
5%.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI // C07B 61/00 300 C07B 61/00 300 (56) References JP-A-61-65840 (JP, A) JP-A-61-189247 ( JP, A) JP-A-60-78949 (JP, A) JP-A-60-41645 (JP, A) US Patent 2,384,817 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 51/235 B01J 23/72 B01J 23/76 B01J 25/00 C07C 59/06 C07C 59/125 C07B 61/00 300

Claims (1)

(57) [Claims] 1. A method for producing monoethylene glycol in the presence of water and a catalyst containing copper or copper and zirconium,
A method for producing a glycolic acid salt, comprising adding 0.8 to 1.3 times mol of an alkali metal hydroxide to monoethylene glycol to be subjected to a reaction to oxidize and dehydrogenate.