WO2010057544A1

WO2010057544A1 - Method for removing hydrogen cyanide from ethane dinitrile

Info

Publication number: WO2010057544A1
Application number: PCT/EP2009/005836
Authority: WO
Inventors: Ellen Klegraf; Andreas Breuer; Wolfgang Wenger
Original assignee: Lonza Ltd
Priority date: 2008-11-20
Filing date: 2009-08-12
Publication date: 2010-05-27
Also published as: AR075100A1; TW201020213A; CH699928A2

Abstract

The invention relates to a method for removing added hydrogen cyanide from ethane dinitrile, characterized in that the gaseous ethane dinitrile comprising hydrogen cyanide is brought into contact with an absorption means.

Description

Process for the removal of hydrogen cyanide from Ethenenitrile

The present invention relates to a process for the removal of hydrogen cyanide from ethanedenenitrile.

Ethenenitrile, also called cyanogen, is a colorless and poisonous, pungent-sweet-smelling gas with a boiling point of -21 ⁰ C. It behaves chemically similar to a halogen and is therefore referred to as pseudohalogen. Ethanenitrile is an important intermediate in the manufacture of many commercial end-products such as artificial fertilizers and nitriles. In addition, Ethandinitrile is used in welding because it burns with oxygen in the hottest known flame (4640 K). Further fields of use of ethanethentril be its use as a high-performance propellant, as a stabilizer in the production of nitrocellulose or as a fumigant, in particular in agriculture such as for killing parasites on agricultural land or in the storage of goods (WO 2005/037332, US 6,001, 383) ,

Usually, ethanedinitrile is obtained industrially by oxidation of hydrogen cyanide, typically using chlorine on an activated silica catalyst or nitrogen dioxide on copper salts. Alternatively, ethanedinitrile can be produced by catalytic oxidation of hydrogen cyanide with hydrogen peroxide in the presence of copper (II) and iron (III) salts, as for example in DE 2 012 509, DE 2 022 454, DE 2 022 455 and DE 2 118 819 described.

Ethenenitrile, which has been obtained, for example, by one of the above methods by oxidation of hydrogen cyanide, usually contains unreacted hydrogen cyanide, as well as by-products such as oxygen, carbon dioxide or water. The purification of ethanedinitrile, especially the selective and quantitative removal of hydrogen cyanide, is extremely demanding. The reason is that ethanedinitrile and hydrogen cyanide have similar chemical behavior and have similar melting and boiling points, so that it is difficult to recover pure ethanedenenitrile by simple condensation or distillation.

It is therefore an object of the present invention to provide an efficient process for the removal of hydrogen cyanide from ethanedenenitrile, in which the yield of pure ethanedenenitrile is as high as possible.

This object is achieved by the method according to claim 1. Further preferred embodiments are the subject of the dependent claims.

BBSTÄTJGüNGSKOPte The present invention relates to a process for the removal of hydrogen cyanide from ethanedenenitrile, characterized in that gaseous, hydrogen cyanide-containing Ethandinitril is brought into contact with an absorbent.

In one embodiment of the invention, a solid is used as absorbent, which binds the hydrogen cyanide, which is contained in the Ethenenitrile as impurity.

In a particularly preferred embodiment, the solid contains silica gel, alumina, or a mixture of silica gel and alumina. Particular preference is given to using silica gel, aluminum oxide or a mixture of silica gel and aluminum oxide as the solid.

Here and below, the term "silica gel" is understood to mean not only silica gel in its pure, colorless form, but also colored silica gels containing metal salts as indicators Examples of colored silica gels are blue gel (contains cobalt (II) chloride) and Orange gel (contains ammonium iron (III) sulfate).

Usually, silica gels are used for the removal of water, i. used for the drying of water-containing substances. In the case of colored silica gel, the color of the metal salt changes due to complex formation. Surprisingly, it has been found that silica gel, alumina, or a mixture of these two substances selectively absorbs hydrogen cyanide, while not chemically absorbing the chemically similar ethanedenenitrile. Since silica gel and aluminum oxide bind not only hydrogen cyanide but also water, at the same time at most any water contained in the crude product is removed. As a result, an additional drying step of the purified ethanedenenitrile can be avoided. Both solids can be regenerated by heating, for example, and used several times. They are also commercially available and inexpensive.

In a further preferred embodiment, the absorbent is a liquid which dissolves the hydrogen cyanide. In a particularly preferred embodiment, the liquid is selected from the group consisting of acetic anhydride, water, ethylene glycol monoether, ethylene glycol diether, propylene glycol monoether, propylene glycol diether, butylene glycol monoether, butylene glycol diether, diethylene glycol monoether, diethylene glycol diether, triethylene glycol monoether, triethylene glycol diether, and mixtures of the aforementioned glycol ethers.

Acetic anhydride is particularly suitable because it is relatively cheap and transportation, storage and disposal are very straightforward. As acetic anhydride due to its high reactivity, the water contained in the Ethandinitril removed, can be dispensed with an additional drying step of the product gas.

Alternatively, water is particularly preferably used as the absorbing liquid. As the pH changes upon dissolution of the hydrogen cyanide, an aqueous basic solution is added to the pH control during the introduction of the gas mixture to be purified into the water. Suitable bases are, for example, sodium hydroxide or potassium hydroxide. Water has the advantage that it is cheap. In addition, the resulting solution of sodium or potassium cyanide may optionally be used to recover these salts. The hydrogen cyanide-containing water can be disposed of in a known per se, for example by hydrolysis or oxidation. Another advantage is that any impurities of the purified according to the invention Ethendnnnnn can be easily removed by the water used, for example by means of drying reagents such as silica gel or alumina.

Alternatively, it is also particularly preferable to use a glycol ether as the absorbing liquid. Suitable glycol ethers are ethylene glycol monoethers, such as, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; Ethylene glycol diethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol diisopropyl ether and ethylene glycol dibutyl ether; Propylene glycol monoethers, such as, for example, 1,2-propylene glycol monomethyl ether, 1,2-propylene glycol monoethyl ether, 1,3-propylene glycol monomethyl ether and 1,3-propylene glycol monoethyl ether; Propylene glycol diethers such as, for example, 1,2-propylene glycol dimethyl ether, 1,2-propylene glycol diethyl ether, 1,2-propylene glycol methyl ethyl ether, 1,2-propylene glycol dipropyl ether, 1,2-propylene glycol methyl butyl ether, 1,3-propylene glycol dimethyl ether, 1,3-propylene glycol dimethyl ether, 1, 3-propylene glycol diethyl ether, 1, 3-propylene glycol methyl ethyl ether and 1, 3-propylene glycol dipropyl ether; Butylene glycol monoether such as butylene glycol monoethyl ether; Butylene glycol diether such as 1,2-butylene glycol dimethyl ether; Diethylene glycol monoether, such as diethylene glycol monomethyl ether (methyl carbitol ^®), diethylene glycol monoethyl ether (Carbitol ^®), Diethylenglykolmonopropylether, diethylene glycol butyl ether (butyl carbitol ^®) and diethylene glycol monohexyl ether (hexyl carbitol ^®); Diethylene glycol diethers such as, for example, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether and diethylene glycol dibutyl ether; triethylene glycol monoether such as triethylene glycol monomethyl ether; Triethylene glycol diethers such as triethylene glycol dimethyl ether and mixtures of the aforementioned glycol ethers. It is advantageous that due to the high boiling points of the glycol ethers to be used according to the invention, the absorbed hydrogen cyanide can be removed by thermal treatment so that the liquids thus obtained can be used again. These glycol ethers are also commercially available and make no special demands on storage and transport.

In a further preferred embodiment, the absorbent is an aqueous, basic solution which absorbs the hydrogen cyanide to form salts. The basic, aqueous solution preferably comprises at least one base selected from the group consisting of sodium carbonate, potassium carbonate, cesium carbonate, magnesium carbonate, sodium bicarbonate, potassium hydrogencarbonate, sodium citrate, potassium citrate, trisodium phosphate, tripotassium phosphate, magnesium thiosulphate, sodium benzoate, sodium hydrogenphosphite, sodium succinate, sodium sulphite , Sodium tartrate, potassium tartrate, sodium potassium tartrate, sodium thiosulfate, potassium benzoate, sodium lactate, potassium lactate, magnesium lactate, and methylamine. An excess of base is not necessary, so that it is preferably used in stoichiometric amount. By adjusting the pH of the basic aqueous solution, hydrogen cyanide can be selectively washed out of the product mixture. The disposal of the spent reagents is easy and environmentally friendly by high-pressure hydrolysis.

In a further preferred embodiment, the absorbent is an aqueous metal salt solution which absorbs the hydrogen cyanide to form a complex. The aqueous metal salt solution preferably contains at least one metal ion selected from the group consisting of Fe ²⁺ , Fe ³⁺ , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Zn ²⁺ , Cu ⁺ , Ag ⁺ , Pb ²⁺ , Cd ²⁺ , Au ⁺ , Hg ²⁺ , Co ²⁺ , Pt ²⁺ and Pd ²⁺ . The removal of the hydrogen cyanide is based on a complex formation reaction of the cyanide ion from the hydrogen cyanide with the metal ions to form a dative bond and is highly selective. Also, the yield of pure Ethandinitril is very high. The use of the metal ions used according to the invention has the advantage that the metal ions can be recycled. Since these are sometimes very valuable, the process costs can be so massively reduced. Furthermore, depending on the metal ion used, several cyanide ions can coordinate to a metal ion. So you can work with small amounts of metal ions. The complex formation is usually very fast and complete. The complex salts formed are preferably solids that can be readily filtered off. Alternatively, the water can simply be distilled off and then problematic. be disposed of. Possible impurities of the purified according to the invention Ethandinitrils by the water from the aqueous metal salt solution can be removed very easily, for example by means of drying reagents such as silica gel or alumina.

In a preferred embodiment, the ethenenenitrile freed of hydrogen cyanide by the process according to the invention is dried and / or brought to condensation or desublimation.

For drying, that is to say for removing water, the hydrogenation-displaced ethanedenenitrile is preferably brought into contact with a sorbent. Suitable sorbents are, for example, silica gel, sodium sulfate, magnesium sulfate, calcium chloride, calcium sulfate, calcium oxide, soda lime, barium oxide, potassium carbonate, phosphorus pentoxide or molecular sieves. Alternatively, the Ethenenitrile can also be freed by freezing water.

The condensing or desublimation of the ethanethene nitrile serves, in particular, to remove carbon dioxide. For this purpose, the freed of hydrogen cyanide and possibly dried Ethenenitrile is cooled to a temperature at which

Ethandinitrile becomes liquid or solid, but not carbon dioxide. By simple

Separation of the phases then the carbon dioxide can be separated from the Ethenenitrile.

Preferably, the condensation or the freezing at normal pressure or an overpressure, for example between about 1 to 15 bar, and a

Temperature of -78 ⁰ C to 30 ° C carried out, in particular at a temperature of -78 ⁰ C to 20 ⁰ C.

Examples

Example 1 Preparation of Ethenenitrile and Purification with Silica Gel (Blaugel)

In a 2 L stirrer (Labmax) with a temperature-controlled jacket, stirrer, reflux condenser, pH probe and two metering devices, 25.3 g of iron (III) sulfate hydrate and 24.7 g of copper (II) sulfate pentahydrate were added in 308 ml_ Water dissolved. Within 120 min at a temperature of 20 ⁰ C 100 g of hydrogen cyanide (100%) and 209 g of hydrogen peroxide (30% strength) were added dropwise in parallel.

The gas resulting from the reaction had, according to gas chromatographic analysis, the following composition: Ethenenitrile: 90.50%

Hydrogen cyanide: 1, 80%

Water: 0.55%

Carbon dioxide: 7,20%

The gas mixture was passed through a gas scrubber with blue gel (CoCb-stained silica gel) and then dried through a gas washing bottle filled with molecular sieve (3 Å). After these purification and drying steps, the ethanedronitrile gas had the following composition according to gas chromatographic analysis:

Ethenenitrile: 90.50% Hydrogen cyanide: -

Water: -

Carbon dioxide: 9.40%

The resulting Ethandinitril was selectively frozen in a cold trap at -78 ⁰ C. The escape of the gaseous carbon dioxide could be followed in a downstream absorber with 20% aqueous potassium hydroxide solution.

The yield of pure Ethenenitrile was 24 g (25%).

Example 2: Preparation of Ethenenitrile and Purification with Aluminum Oxide

In a 2 L stirrer (Labmax) with temperature-controlled jacket, stirrer, reflux condenser, pH probe and two dosing devices 2.5 g of iron (III) sulfate hydrate and 2.5 g of copper (II) sulfate pentahydrate in 308 mL Water dissolved. Within 120 min at a temperature of 20 ⁰ C 100 g of hydrogen cyanide (100%) and 126 g of hydrogen peroxide (50%) were added dropwise in parallel.

The gas resulting from the reaction had, according to gas chromatographic analysis, the following composition:

Ethenenitrile: 95.20%

Hydrogen cyanide: 2.20%

Water: 0.50%

Carbon dioxide: 2.10% The gas mixture was passed through a gas scrubber with alumina and then dried through a bubbler filled with molecular sieve (3 Å). After these purification and drying steps, the ethanandntrile was obtained in 43% yield and by gas chromatographic analysis with the following composition:

Ethenenitrile: 97.40%

Hydrogen cyanide: 0.50% water: -

Carbon dioxide: 2.10%

Example 3 Preparation of Ethandinitrile and Purification with Diethylene Glycol Monoethyl Ether

In a 2 L stirrer (Labmax) with a temperature-controlled jacket, stirrer, reflux condenser, pH probe and two metering devices, 7.5 g of iron (III) sulfate hydrate and 7.5 g of copper (II) sulfate pentahydrate were added 308 ml_ water dissolved. Within 180 min at a temperature of 25 ⁰ C 100 g of hydrogen cyanide (100%) and 209 g of hydrogen peroxide (30%) were added dropwise in parallel.

Ethenenitrile: 95.60%

Hydrogen cyanide: 2.09%

Water: 0.57%

Carbon dioxide: 1, 68%

The gas mixture was passed through a gas scrubber with diethylene glycol monoethyl ether (Carbitol ^®) and subsequently filled for drying through a molecular sieve (3 A) gas washing bottle. After these purification and drying steps, the ethanedronitrile gas had the following composition according to gas chromatographic analysis:

Ethenenitrile: 94.60%

Hydrogen cyanide: 0.40%

Water: -

Carbon dioxide: 4.93% The resulting Ethandinitril was selectively frozen in a cold trap at -78 ⁰ C. The escape of the gaseous carbon dioxide could be followed in a downstream absorber with 20% aqueous potassium hydroxide solution.

The yield of pure ethanedenenitrile was 73 g (68%).

Example 4: Preparation of Ethenenitrile and Purification with Acetic Anhydride

In a 2 L stirrer (Labmax) with temperature-controlled jacket, stirrer, reflux condenser, pH probe and two dosing devices 2.5 g of iron (III) sulfate hydrate and 2.5 g of copper (II) sulfate pentahydrate in 308 mL Water dissolved. Within 150 min at a temperature of 20 ⁰ C 100 g of hydrogen cyanide (100%) and 126 g of hydrogen peroxide (50%) were added dropwise in parallel.

Ethenenitrile: 92.00%

Hydrogen cyanide: 1, 70%

Water: 0.50%

Carbon dioxide: 5.80%

The gas mixture was passed through a gas scrubber with acetic anhydride and then dried through a drying tower filled with molecular sieve (3 Å). After these purification and drying steps, the ethenenonitrile was obtained in 52% yield and by gas chromatographic analysis with the following composition:

Ethenenitrile: 88.20%

Hydrogen cyanide: 0.20% water: -

Carbon dioxide: 1 1, 60%

Example 5: Preparation of Ethenenitrile and Purification with Water

25.3 g of iron (III) sulfate hydrate and 24.7 g of copper (II) sulfate pentahydrate in 308 ml Water dissolved. Within 100 g of hydrogen cyanide (100%) and 209 g hydrogen peroxide (30% strength) were added dropwise over 120 min in parallel at a temperature of 20 ⁰ C.

Ethenenitrile: 91, 60%

Hydrogen cyanide: 2.00%

Water: 0.57%

Carbon dioxide: 5.83%

The gas mixture was passed through a gas scrubber with water, during which process the pH of the water was adjusted to a pH between 6 and 7 with 10% sodium hydroxide solution. Subsequently, the resulting gas mixture was passed to dry through a cooled to -10 ⁰ C reflux condenser. After these purification and drying steps, the ethanedronitrile gas had the following composition according to gas chromatographic analysis:

Ethenenitrile: 92.60%

Hydrogen cyanide: 0.40%

Water: 0.08%

Carbon dioxide: 6.93%

The yield of pure ethanedenenitrile was 58 g (56%).

Example 6: Preparation of Ethandinitrile and Purification with Sodium Carbonate Solution

25.3 g of iron (III) sulfate hydrate and 24.7 g of copper (II) sulfate pentahydrate in 308 ml Water dissolved. Within 140 minutes at a temperature of 20 ⁰ C 77 g of hydrogen cyanide (100%) and 144.6 g of hydrogen peroxide (30% strength) were added dropwise in parallel.

The gas resulting from the reaction had, according to gas chromatographic analysis, the following composition: Ethenenitrile: 90.90%

Hydrogen cyanide: 1, 73%

Water: 0.56%

Carbon dioxide: 6.80%

The gas mixture was passed through a gas scrubber with aqueous 5% sodium carbonate solution and then dried through a drying tower filled with molecular sieve (3 Å). After these purification and drying steps, the ethanedronitrile gas had the following composition according to gas chromatographic analysis:

Ethenenitrile: 90.00%

Hydrogen cyanide: 0.13%

Water: 0.04%

Carbon dioxide: 9.80%

Example 7: Preparation of Ethandinitrile and Cleaning with Copper (II) Sulfate Solution

25.3 g of iron (III) sulfate hydrate and 24.7 g of copper (II) sulfate pentahydrate in 308 ml Water dissolved. Within 360 min at a temperature of 20 ⁰ C 300 g of hydrogen cyanide (100%) and 632 g of hydrogen peroxide (30%) were added dropwise in parallel.

Ethenenitrile: 95.37%

Hydrogen cyanide: 1, 95%

Water: 0.53%

Carbon dioxide: 2.15%

The gas mixture was passed through a scrubber with 20% aqueous copper (II) - sulfate solution and then dried by passing through a gas cylinder filled with molecular sieve (3 Ä). After these cleaning and drying steps the Ethandinitril gas according to gas chromatographic analysis had the following composition:

Ethenenitrile: 97.20% Hydrogen cyanide: -

Water: -

Carbon dioxide: 2.80%

The yield of pure Ethenenitrile was 225 g (78%).

Example 8: Preparation of Ethenenitrile and Purification with Iron (II) Sulfate Solution

In a 2 L stirrer (Labmax) with a temperature-controlled jacket, stirrer, reflux condenser, pH probe and two metering devices, 25.3 g of iron (III) sulfate hydrate and 24.7 g of copper (II) sulfate pentahydrate were added Dissolve 308 mL of water. Within 120 min at a temperature of 15 ⁰ C 100 g of hydrogen cyanide (100%) and 251 g of hydrogen peroxide (30%) were added dropwise in parallel.

The gas mixture formed during the reaction was passed through a gas scrubber with 10% strength aqueous iron (II) sulfate solution without subsequent gas chromatographic analysis and then through a reflux condenser cooled to -10.degree. After these purification and drying steps, the ethanandntrile was obtained in 74% yield and by gas chromatographic analysis with the following composition:

Ethenenitrile: 89.60%

Hydrogen cyanide: 0.05%

Water: 0.15%

Carbon dioxide: 10.15%

Claims

claims

1. A process for the removal of added hydrogen cyanide from Ethandinitril, characterized in that gaseous, hydrogen cyanide-containing Ethandinitril is brought into contact with an absorbent.

2. The method according to claim 1, characterized in that the absorbent is a solid which binds the hydrogen cyanide.

3. The method according to claim 2, characterized in that the solid contains silica gel, alumina or a mixture of silica gel and alumina.

4. The method according to claim 1, characterized in that the absorbent is a liquid which dissolves the hydrogen cyanide in the liquid.

5. A process according to claim 4, wherein the liquid is selected from the group consisting of acetic anhydride, water, ethylene glycol monoether, ethylene glycol diether, propylene glycol monoether, propylene glycol diether, butylene glycol monoether, butylene glycol diether, diethylene glycol monoether, diethylene glycol diether, triethylene glycol monoether, triethylene glycol diether and mixtures of previously mentioned glycol ether is selected.

6. The method according to claim 1, characterized in that the absorption medium is an aqueous, basic solution which absorbs the hydrogen cyanide with salt formation.

7. The method according to claim 6, characterized in that the aqueous, basic solution contains at least one base selected from the group consisting of sodium carbonate, potassium carbonate, cesium carbonate, magnesium carbonate, sodium bicarbonate, potassium bicarbonate, sodium citrate, potassium citrate, trisodium phosphate, tripotassium phosphate, magnesium thiosulfate , Sodium benzoate, sodium hydrogen phosphite, sodium succinate, sodium sulfite, sodium tartrate, potassium tartrate, sodium potassium tartrate, sodium thiosulfate, potassium benzoate, sodium lactate, potassium lactate, magnesium lactate and methylamine.

8. The method according to claim 1, characterized in that the absorbent is an aqueous metal salt solution which absorbs the hydrogen cyanide with complex formation.

9. The method according to claim 8, characterized in that the aqueous metal salt solution contains at least one metal ion selected from the group consisting of Fe ²⁺ , Fe ³⁺ , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Zn ²⁺ , Cu ⁺ , Ag ⁺ , Pb ²⁺ , Cd ²⁺ , Au ⁺ , Hg ²⁺ , Co ²⁺ , Pt ²⁺ and Pd ²⁺ .

10. The method according to any one of claims 1 to 9, characterized in that the liberated from hydrogen cyanide Ethandinitril dried and / or brought to condensation or desublimation.