JPH0237911B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new process for producing ethylenediaminetetraacetate from tetraethanolethylenediamine. More specifically, the present invention relates to characteristic reaction conditions, additives, and catalysts for producing ethylenediaminetetraacetate by reacting tetraethanolethylenediamine in the presence of an alkali metal hydroxide.

The production of ethylenediaminetetraacetic acid sodium from tetraethanolethylenediamine proceeds according to reaction formula (1) as shown below, and the production of ethylenediaminetetraacetic acid from ethylenediaminetetraacetic acid soda proceeds according to reaction formula (2).

(HOCH ₂ CH ₂ ) ₂ NCH ₂ CH ₂ N (CH ₂ CH ₂ OH) ₂ +4NaOH Water, catalyst――――――→ (NaOOCCH ₂ ) ₂ NCH ₂ CH ₂ N (CH ₂ COONa) ₂ +8H ₂ … …(1) (NaOOCCH ₂ ) ₂ NCH ₂ CH ₂ N (CH ₂ COONa) ₂ +2HSO ₄ ------→ (HOOCCH ₂ ) ₂ NCH ₂ CH ₂ N (CH ₂ COOH) ₂ +2Na ₂ SO ₄ ... (2) Due to its excellent chelating ability, ethylenediaminetetraacetate is used as a water softener, scouring aid, dyeing aid, paper coating agent, scale inhibitor,
It is used in a wide range of fields such as detergent builders and detergents for soap.

As industrial methods for producing ethylenediaminetetraacetate, the Strecker method using hydrocyanic acid and formaldehyde as main raw materials and the method of reacting monochloroacetic acid with ethylenediamine are generally known today. However, in the case of the Stretzker process, since hydrocyanic acid is a highly poisonous gas, there are major restrictions in terms of production equipment, handling, and location.Furthermore, most of the hydrocyanic acid is obtained as a by-product during the production of acrylonitrile, which poses a major problem in securing a stable supply of raw materials. It was hot. Furthermore, when monochloroacetic acid is used, there is a drawback that the manufacturing cost is high due to high raw material costs.

On the other hand, a method for producing ethylenediaminetetraacetate by oxidative dehydrogenation of tetraethanolethylenediamine in caustic alkali is disclosed in US Pat.
2384816, U.S. Patent No. 2384817, U.S. Patent No.
It is disclosed in No. 3535373. US Patent No. 2384816
Example 2 of the above publication discloses a method of reacting tetraethanolethylenediamine and potassium hydroxide without a catalyst, but the reaction time is long and the yield is low. U.S. Patent No. 2348817, U.S. Patent No.
No. 3,535,373 discloses a method using cadmium oxide as a catalyst, and in these examples, the highest yield of ethylenediaminetetraacetic acid is 84.8%.

As described above, in the conventional technology, the yield is too low in a reaction without a catalyst, and in a reaction using cadmium oxide as a catalyst, there is a risk that cadmium compounds, which are toxic substances, may be mixed into the reaction product, so depending on the application. It cannot be used at all, and if it flows into rivers as wastewater, it would cause major social problems, so until now it could not become a technology that could compete with the Stretzker method or the acrylonitrile acetic acid method.

The present inventors have conducted intensive research on the oxidative dehydrogenation method of tetraethanolethylenediamine as a method for producing ethylenediaminetetraacetate that can be used as an alternative to these methods. They discovered a new method for producing ethylenediaminetetraacetate in high yield and completed the present invention.

The present invention relates to a method for producing ethylenediaminetetraacetate, which comprises reacting tetraethanolethylenediamine with an alkali metal hydroxide, water, and copper in the presence of a catalyst containing a zirconium compound.

A feature of the present invention is that when producing ethylenediamine tetraacetate from tetraethanolethylenediamine, a safe catalyst containing a copper and zirconium compound is used without using a cadmium catalyst.

Even without a zirconium compound, copper-containing catalysts can be used under very mild conditions of 140 to 220°C to increase the yield of ethylenediaminetetraacetate to 70% based on tetraethanol ethylenediamine.
~80 mol%. However, the catalyst containing copper and zirconium compounds not only has the effect of improved heat resistance and longer catalyst life, but also improves selectivity and catalytic activity, and has an ethylenediaminetetraacetate yield of 82 to 87 mol%. It became possible to lower the reaction temperature by 10 to 20°C. By implementing the present invention, compared to conventional methods, the yield of ethylenediaminetetraacetate can be improved, the reaction time can be shortened,
Mild reaction conditions became possible. As a result, we have completed a revolutionary method for producing ethylenediaminetetraacetate using the oxidative dehydrogenation method of tetraethanolethylenediamine, which enables a significant reduction in the production cost of ethylenediaminetetraacetate and is easy to implement industrially. be.

In one embodiment of the present invention, the catalyst used in the method of the present invention contains copper and a zirconium compound as essential components.

The catalyst can be used as it is or supported on an alkali-resistant carrier. The amount of catalyst used is 1 to 70% of tetraethanol ethylenediamine.
% by weight, preferably in the range 10-30% by weight.
The catalyst containing copper and zirconium compounds of the present invention can be used as raw materials for copper or zirconium compounds, including inorganic salts such as nitrates, sulfates, carbonates, oxides, halides, and hydroxides, as well as acetates, oxalates, and citrates. Organic salts such as acid salts and lactate salts can be used. In particular, highly water-soluble salts are preferred. Specific examples of zirconium compounds include zirconium oxynitrate, zirconium nitrate, zirconium oxysulfate, zirconium sulfate, zirconium oxycarbonate, zirconium carbonate, zirconium oxide, zirconium oxychloride, zirconium tetrachloride, ethylene hydroxide, zirconium oxyacetate, and zirconium acetate. , zirconium oxalate, and the like. Although the form of the catalyst is not particularly limited, an alkaline aqueous solution is added to a solution of a copper compound and a zirconium compound dissolved in water to precipitate a hydroxide, and this precipitate is washed with water and dried.
Catalysts containing copper and zirconium compounds that have been calcined and then reduced in a hydrogen atmosphere are preferred. Further, a catalyst containing a copper and zirconium compound obtained by impregnating zirconium oxide with an aqueous solution of a copper compound, drying, calcining, and reducing the catalyst in a hydrogen atmosphere is preferably used.

Since the catalyst usually has low reaction activity, it can be used repeatedly, but it can also be used once.

Since water in the reaction of the present invention is a homogeneous system of tetraethanol ethylene diamine and alkali metal hydroxide, the reaction conditions can be made mild.
It is essential for obtaining high yields of ethylenediaminetetraacetate. The amount of water used in the reaction is at least 10% by weight, preferably in the range of 100 to 500% by weight, based on tetraethanol ethylene diamine.

The alkali metal hydroxide used in the present invention includes lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide. Among these, sodium hydroxide and potassium hydroxide are particularly preferably used. The amount of alkali metal and/or alkaline earth metal hydroxide used is at least an equivalent equivalent to the conversion rate of tetraethanolethylenediamine used in the reaction, preferably
It is in the range of 1.0 to 2.0 equivalents. As the alkali metal hydroxide, any of flakes, powders, pellets, etc. and aqueous solutions thereof can be used, but aqueous alkali metal solutions are generally preferably used because they are convenient in terms of handling.

Tetraethanolethylenediamine is preferably of high purity in order to avoid contamination of the ethylenediaminetetraacetate with impurities. Although there are no particular limitations on the purity, a purity of 96% by weight or more, preferably 99% by weight is used.

The reaction temperature was set to prevent thermal decomposition and hydrogenolysis of the C--N bond in tetraethanol ethylene diamine and the C--N bond in ethylene diamine tetraacetate.
Temperature below 220℃, usually 140-220℃, preferably
It is carried out at a temperature range of 150-210°C. Additionally, catalysts containing copper and zirconium compounds are heated at 220°C.
Temperatures below 220°C are more preferable when the catalyst is used repeatedly, since sintering occurs on a portion of the surface at temperatures exceeding 220°C, resulting in a decrease in surface area and a decline in catalytic activity. Since the reaction is an oxidative dehydrogenation reaction, it is preferable to lower the reaction pressure as much as possible from the viewpoint of reaction rate. Usually, the minimum pressure for proceeding the reaction in the liquid phase or higher, preferably 0~
It is in the range of 20 Kg/cm ² G, more preferably 5-15 Kg/cm ² G.

The reaction time can be selected as appropriate and is determined by the reaction temperature, amount of catalyst, and reaction pressure. For example, reaction temperature
In the case of 185° C., reaction pressure of 10 Kg/cm ² G, and a catalyst amount of 10% by weight based on tetraethanol ethylene diamine, the reaction time is 6 to 8 hours.

As for the reaction format, any of batch, semi-batch and continuous reaction methods can be used.

Hereinafter, embodiments of the present invention will be specifically illustrated and explained with reference to Examples. The present invention is not limited to these examples.

Here, the conversion rate of tetraethanolethylenediamine and the selectivity of ethylenediaminetetraacetate are derived from the following equation.

Conversion rate of tetraethanol ethylenediamine (%) Reacted tetraethanol = Number of moles of ethylenediamine / Tetraethanol used for reaction x 100 Number of moles of ethylenediamine Selectivity of ethylenediaminetetraacetate (%) Ethylenediamine produced = Moles of tetraacetate Number/Reacted tetraethanol x 100 Number of moles of ethylenediamine Example 1 Tetraethanol ethylenediamine 82.6g, sodium hydroxide 58.8g, water 141.4g and as catalysts zirconium oxychloride 24.8g and copper nitrate 4.0
A sodium hydroxide aqueous solution was added to a solution of g in 300 ml of water to precipitate the hydroxide, and this precipitate was washed with water and dried, then heat treated in air at 500°C for 3 hours, and then in a hydrogen stream at 230°C for 6 hours. Catalyst containing copper and zirconium compound obtained by reduction treatment
8.3 g of the autoclave was charged into a 500 ml autoclave, and after internal purge with hydrogen gas three times, the reaction was carried out at a reaction temperature of 185° C. and a reaction pressure of 10 Kg/cm ² G until no more hydrogen was generated. The time required for the reaction was 6 hours after the temperature was raised to 185°C. After the reaction was completed, the reaction solution was taken out and analyzed, and the conversion rate of tetraethanolethylenediamine was 98.8 mol%, and the selectivity of ethylenediaminetetraacetic acid sodium was 86.0 mol%.

Example 2 82.6 g of tetraethanol ethylene diamine, 58.8 g of sodium hydroxide, 141.4 g of water, and as a catalyst, 10 g of zirconium oxide was impregnated with an aqueous solution containing 4.2 g of copper nitrate, and after drying, the mixture was heated at 500° C. in air.
8.3 g of the copper supported catalyst on zirconium oxide obtained by heat treatment for 3 hours and reduction treatment at 230°C in a hydrogen stream for 6 hours was charged into a 500 ml autoclave, and after internal displacement with hydrogen gas three times, the reaction was carried out. temperature
The reaction was carried out at 185° C. and a reaction pressure of 10 Kg/cm ² G until no hydrogen was generated. The time required for the reaction is
It was 6.5 hours after the temperature was raised to 185°C. After the reaction was completed, the reaction solution was taken out and analyzed, and the conversion rate of tetraethanolethylenediamine was 98.5 mol%, and the selectivity of ethylenediaminetetraacetic acid sodium was 85.8.
It was in mol%.

Example 3 In order to check the repeated activity of the catalyst, repeated experiments were conducted under the same reaction conditions as in Example 1.
The reaction time required for the 10th reaction was 8.5 hours after the temperature was raised. After the reaction was completed, the reaction solution was taken out and analyzed, and the conversion rate of tetraethanolethylenediamine was 97.8 mol%, and the selectivity of ethylenediaminetetraacetic acid sodium was 84.9 mol%.

Claims (1)

[Claims] 1. A method for producing ethylenediaminetetraacetate, which comprises reacting tetraethanolethylenediamine in the coexistence of an alkali metal hydroxide, water, copper, and a zirconium-containing catalyst.