EDA Purification via Elevated Pressure Distillation
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Solution Overview
Problem
Existing processes for purifying ethylenediamine (EDA) face challenges due to the formation of azeotropic mixtures with water and N-methylethylenediamine, leading to inefficiencies and increased wastewater generation, particularly when the water to EDA ratio is not optimal, resulting in high water content that requires additional separation and purification steps.
Innovation Solution
A process involving two distillation steps where a mixture of water, EDA, and N-methylethylenediamine is first distilled at pressures above 4.8 bara to separate the majority of water, followed by a second distillation to remove N-methylethylenediamine, avoiding azeotropic separations and reducing nitrogen compound contamination in the water stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If azeotropic distillation is used to separate N-MeEDA from EDA at atmospheric pressure, then separation can be achieved, but water accumulates at the bottom of the column requiring additional separation steps and increased complexity
Solution Approach 1:
The patent changes the operating pressure parameter from atmospheric pressure to elevated pressure (greater than 4.8 bara). This parameter change eliminates the formation of the N-MeEDA/water azeotrope and prevents water accumulation at the column bottom, thereby avoiding the need for additional water separation steps and reducing overall process complexity while maintaining separation efficiency
2Manufacturing precision
If water is added to enable azeotropic removal of N-MeEDA, then N-MeEDA separation is improved, but water content in the bottom stream increases requiring additional separation steps
Solution Approach 1:
By changing the pressure parameter to greater than 4.8 bara, the patent eliminates the need to add water for azeotropic removal. The elevated pressure condition inherently prevents water accumulation and N-MeEDA co-distillation, achieving effective N-MeEDA removal without increasing water content in the bottom stream
3Manufacturing precision
If multiple distillation steps are used to separate water and N-MeEDA, then purification efficiency is improved, but operational costs and process time increase
Solution Approach 1:
The patent uses a single distillation step at elevated pressure (greater than 4.8 bara) that simultaneously achieves both water removal and N-MeEDA separation. This eliminates the need for multiple sequential distillation steps, thereby maintaining high purification efficiency while improving operational efficiency and reducing process time
Solution Approach 2:
The patent segments the separation function into a single integrated distillation process that handles both water and N-MeEDA removal in one operation. By designing the column to operate at elevated pressure, both separation objectives are achieved simultaneously rather than requiring separate processing stages
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively separates water and N-methylethylenediamine from EDA without azeotropic conditions, minimizing wastewater nitrogen content and allowing for more efficient purification with lower operational costs, and can be applied to EDA produced through various methods, enhancing catalyst performance by using sulfur dioxide-free hydrocyanic acid.
Implementation Method 1
a) a mixture (G1) comprising water, EDA and N-methylethylenediamine (N-MeEDA) is fed into a distillation apparatus (D1), and the major part of the water comprised in the mixture (G1) is separated off overhead at a pressure of greater than 4.8 bara
Implementation Method 2
EDA and N-MeEDA form a close-boiling azeotropic mixture at atmospheric pressure, and this generally cannot be separated with an industrially justifiable outlay
Implementation Method 3
b) the mixture (G2) is fed into a distillation apparatus (D2), with (i) a stream (S2) comprising N-MeEDA being distilled off overhead from (D2)
Data Source
AI summary
The present invention relates to a process for purifying ethylenediamine (EDA) by distillation, wherein the process comprises the steps a) and b). In step a), a mixture (G1) comprising water, EDA and N-methylethylenediamine (N-MeEDA) is fed into a distillation apparatus (D1), and the major part of the water comprised in the mixture (G1) is separated off overhead at a pressure of greater than 4.8 bara. From the bottom of (D1), the water-enriched mixture (G2) is fed into a distillation apparatus (D2) in step b). At the top of (D2), the major part of the N-MeEDA is distilled off. The stream (S3) obtained from the bottom of (D2) comprises EDA, with the components water and N-MeEDA comprised in the mixture (G1) having been largely or completely removed. Further distillation steps can optionally be carried out in order to obtain pure EDA, for example when diethylenetriamine (DETA) is additionally comprised in the mixture (G1). If ammonia is additionally comprised in the mixture (G1), an ammonia removal is preferably additionally carried out before carrying out the step a) in the process of the invention.