DD217508A1 - METHOD FOR ISOLATING WATER-FREE ETHYLENEDIAMINE - Google Patents

Abstract

Process for the isolation of anhydrous ethylenediamine from the reaction products of the amination of monoethanolamine with ammonia. The isolation is carried out in two stages, wherein in the first stage, a pressure of 0.15 to 0.35 MPa and ammonia is used as a distillation aid. In the second distillation stage operating at atmospheric pressure, anhydrous ethylenediamine is obtained.

Description

L? 8348

• Title of the invention. .

Process for the isolation of anhydrous ethylenediamine: Field of application of the invention

The invention relates to a "/ learn for the isolation of anhydrous ethylenediamine (EDA) from a reaction mixture of the amination of monoethanolamine (IvIEA) by distillation.

Characteristic of the known technical solutions

In the catalytic amination of ESA, in addition to SDA and water, even higher-boiling polyamines are formed. Water and. EDA form an azeotropic mixture at IT crmal pressure with a maximum boiling point of 392 K and a water content of 22% by mass. Therefore, the ^j Irennung- of EDA and T / ater by fractional distillation is not possible.

It is known to isolate SDA from water / EDA-C-emischen by azeotropic distillation with hydrocarbons (DE-OS 1 995 827) or amines (DE-OS 1 962 285) as aseotropic.

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detrimental b.ei this process is in addition to a high energy requirement, a considerable use of chemicals or effort for the realization of a Hilfsstoffkreislaufs.

Furthermore, it is known to distill EDA / water mixtures under a pressure of 0.5 to .0.6 MPa (DE-AS 1 263 776), because at a pressure of 2 0.48 HPa the azeotrope of the EDA with Γ Water-not more * exists «

This process has the disadvantage that, in addition to a high expenditure of energy and apparatus, only one SDA / water mixture, which must be free of higher di- and polyethylenepolyamines, can be used «

It is also known to realize the separation of EDA / water mixtures with an extractive distillation. The solvents used are: ¹⁾ sodium hydroxide, polyamines, diphenyls, alkanolamines and also polyols and glycol ethers (US Pat. No. 3,055,800). The advantage of the extractive distillation is that EDA and the solvent are present in an additional column must be separated from each other that there are additional separation problems, if in the EDA / water mixture still other higher-boiling amines present ^; and that solvent losses must be supplemented ·,.

The addition of distillation aids, these distillation aids are higher-boiling: polyamines, as 'they can be formed in the amination of MEA,' is described in DE-OS ····················. However, there is no complete separation of EDA water in one stage, despite high bottoms of the distillation columns. "In a first distillation column, pure water is withdrawn overhead, while the bottom product is a water-and-EDA-type Product remains, from which in a second stage or column a water / EDA Ge. Mixture is distilled off, in which the water content. Below the azeotropic Punkt.liegt, in a third distillation column

is then distilled off in vacuo practically anhydrous EDA (practically anhydrous means that the water content is less than 1 Ma - . % ), while the bottom product, the azeotrope 'water /. EDA. remains, which is recycled back to the first distillation column.

This process has the disadvantage that for the recovery of virtually anhydrous SDA from the reaction product of the amination of HEA a total of 3 columns are needed. In addition, considerable amounts of EDA / vasasser mixtures are circulated and thus have to be evaporated several times, so the process is very energy-intensive.

Object of the invention. ,

The aim of the invention is to develop a process for the economically favorable separation of EDA and water in mixtures, as they arise in the amination of IaEA. ^:

Explanation of the essence of the invention

It was therefore the object to achieve the isolation of anhydrous SDA from mixtures of di- and polyethylenepolyamines with simple distillations without recycling, excipients and target products.

This object is achieved by a method for the isolation of anhydrous EDA from the reaction products of the amination of MEA according to the invention that from the mixture of the reaction products at a pressure of 0.15 to 0.25 LiPa \ the 7 / asser in the presence of ammonia as Distilled distillate in a distillation column and distilled off from the 'sump product of this column in a second distillation column anhydrous EDA. ..

In practice, the mixture of ammonia, water, EDA and polyamines is placed in a continuous process.

injecting working column. The top product is ammonia and water having a very low SDA content, a portion of the top product is recycled as reflux into the column in order to increase its separation effect. From the sump, SDA and the polyamines are withdrawn, which is the sump content of the sump. very low. ,

The bottom number of the column and the reflux ratio depend on the purity requirements for the top and bottom product.

The column pressure depends on the sump temper%, which results after the composition of the sump mixture, and he. is chosen so that the sump temperature does not exceed 473 K, otherwise the polyamines decompose. The head temperature is also pressure dependent, it is at pressures of 0.1-5 to 0.35 MPa 363. to 408 K.

From the bottom product of this column · is then distilled off in a second column practically anhydrous EDA · The Ainmoniakgehalt of the product to be used for this separation.Produkt by introducing ITH, gaseous, but also by

• · - · '-2. , , , Metered addition of liquid or 'aqueous ammonia. It is particularly advantageous if the reaction product is reduced to the distillation pressure after evaporation of TvIEA so that the necessary ammonia remains in the product. It is favorable, if the content of ammonia is so chosen, that in the first Distillation stage a concentrated aqueous ammonia solution is obtained «

embodiments

For the first distillation stage, a continuous working column of "2A steel of 70 mm diameter was used"; which was filled with 4 mm 72A coils. The theoretical number of plates was 61, the inlet point was on the 45th floor calculated from the swamp. '-

Purely the second distillation step, a continuous glass column of 40 mm diameter was used. The theoretical number of fens was 32, the entry point was on the 14th floor of marsh.

The composition of all inlet and distillation products was determined by gas chromatography.

Example 1 _t -

In the first column, an amine mixture obtained from the amination of MEA, the following composition was used:.

Components * Content in% by weight

M ₃ .1,5. , .. .. ' ^:

H ₂ O , '15.6.

SDA '. '16,2; - ''

Piperazine (DEDA) 10.2

MEA. - 34.8: -

Diethylenetriamine (DETA) 7,8

IT (β-amino ethyl) piperate in (AEP) 2.1.

Hydrocyanet triethylenediamine (HEEDA) 6.2

Triethylenetetramine (TETA) 1, β

The distillation conditions were:

Inlet 1,0 -l / h * '

Pressure 0.2 1.IPa

Reflux ratio 7

Head temperature 393 K

Sump temperature. 454 K ''

Distillate attack. 0.2 l / h _:

The top product consisted of a ϊΧΗο / T / asser G-emisch with a 3iE ,, content of 7.0 Ua .-% and an EDA content of 0.14 LIa. -%. The water content of the Smpf product was 0.05 LIa.-fs. , '- .. ·.

The bottom product was distilled in a second column under the following conditions:

Inlet · 0.3 l / h

Print- . ^; 0.1 MPa

Reflux ratio 3 '

Head temperature 389 K. ,

Bottom temperature. 449 K

Top product accumulation .. 0,0b l / h

The top product consisted of SDA with a water content of O, 25Ma, -% and a DEDA content of 0.15 Ma.- £>.

Example 2. ,

EISA was reacted on a Co / Ui / Cu supported catalyst in the presence of hydrogen and excess ammonia at 453K and 20 MPa. The amination product was depressurized to 0.0.15 ICPa and had the following composition: '' ..-- · · '

Components. '' Salary in J £ a .- $

IH ₃ . , '5,5'.

Water . 18.5 ..

EDA '"15.9

DEDA '. 9.8 · '

UNITED STATES' . '32,2' ...

DETA .., - '' '8.0. '. ,

AEP. 2.0

HEEDA, '; 6,4- '

TETA '. 1,7 '

Under this pressure, the amination product was injected into the first column: '

Inlet / 1,0 l / h '

Return ratio 7 ,

Head temperature '382 K. .

Bottom temperature 445 K '' ·, ·.

"Head to all. 0.25 l / h

The: head product consisted of an ESO / water mixture with a BHo content of 23.0 Ha. % and an EDA content of 0.11 Ma%. The water content of the bottom product was 0.10 lia .-%. , , ''

The bottom product was distilled in a second column under the same conditions as in Example 1. The overhead product consisted of EDA with a water content of 0.45 'Ma. -% and a DKDA salary of 0.10 Ma ₁ , -> S.

Example 3 "

An amine mixture as indicated in Example 2 was distilled in the first column under the following conditions;

Inlet 1.0 l / h,

Pressure 0.35 MPa

Reflux ratio 7

Head tempera door 407 K. "

Sump temperate 473 K _:

Distillate attack 0.24 l / h '. '/'.

The overhead product consisted of an ITHo / water mixture with an ammonia content of 23.0 Ma. % and a BDA Geha It of 0.08% by mass. In the bottom product - no water was detectable, the water content was below 0.05 Ma.-ί-δ. '

The bottoms of the first column was in the second column under the same conditions, τ / ie in Example 1, distilled. The top product consisted of SDA with a water content of 0.10 Ma .- ^ and a DEDA content of also 0.10 Ma. -fj. The higher boiling amines remained in the sump.

Claims (2)

Srfindun claim '\. .1 'A process for the isolation of anhydrous ethylenediamine' from the reaction products of the amination of monoethanolamine, characterized in that the mixture of 'reaction products at a pressure of 0.15 to 0.35 ICPa in the presence of ammonia as a distillation aid in a distillation column distilled off the water as the top product and that an anhydrous ethylenediamine is obtained from the bottom product of this column in a second distillation column at! Tormaldruck as distillate * 2 »Method according to item 1, characterized in that the amount of ammonia in the reaction product.The amination of monoethanolamine 0.5 to 10 Ha. -% is,