Extractive Distillation of Monoethylene Glycol and Diethylenetriamine
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The separation of monoethylene glycol (MEG) and diethylenetriamine (DETA) by distillation is challenging due to their azeotropic nature, making it difficult to achieve high purity of individual products using pressure swing distillation.
Innovation Solution
The process employs extractive distillation with triethylene glycol (TEG) as a selective solvent to separate MEG and DETA, resulting in streams that are largely free of each other, with DETA content less than 5% by weight in the MEG stream and MEG content less than 2% by weight in the DETA stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pressure swing distillation is used to separate MEG and DETA, then the distillation process is simple, but the separation purity is insufficient due to azeotropic formation
Solution Approach 1:
The patent introduces a third component (azeotroping agent such as water, ethanol, or isopropanol) that acts as an intermediary to break the azeotropic relationship between MEG and DETA. This agent forms a new azeotrope with one of the components, enabling effective separation that cannot be achieved by simple or pressure-swing distillation alone. The intermediary substance modifies the vapor-liquid equilibrium to achieve the desired separation purity.
2Manufacturing precision
If extractive distillation with TEG is used to achieve high purity separation, then separation purity is improved, but device complexity and operating cost increase
Solution Approach 1:
The patent changes the chemical composition parameter of the distillation system by adding a selective solvent (triethylene glycol or other high-boiling glycols). This parameter change fundamentally alters the relative volatility between MEG and DETA, enabling high-purity separation. The solvent is chosen based on its selective interaction with one component, creating a system where one component is preferentially retained in the liquid phase while the other vaporizes.
3Manufacturing precision
If multiple distillation steps are used to achieve high purity, then separation purity is improved, but energy consumption and processing time increase
Solution Approach 1:
The patent performs preliminary action by adding the azeotroping agent or selective solvent before the distillation process begins. This pre-treatment step modifies the mixture's properties to facilitate easier and more energy-efficient separation. By preparing the system in advance with the appropriate additive, the subsequent distillation requires fewer theoretical stages and less reboiler duty to achieve the same purity level.
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 method effectively separates MEG and DETA, achieving purity levels of less than 0.1% by weight of DETA in the MEG stream and less than 10 ppm, and less than 0.1% by weight of MEG in the DETA stream, overcoming the limitations of azeotropic distillation.
Implementation Method 1
the separation is carried out by extractive distillation with triethylene glycol as the selective solvent for diethylenetriamine
Data Source
AI summary
A process is proposed for the distillative separation of a mixture comprising monoethylene glycol and diethylenetriamine, to form a stream (7) which contains monoethylene glycol and is largely free from diethylenetriamine, and a stream (8) which contains diethylenetriamine and is largely free from monoethylene glycol, the process being characterized in that the separation is carried out by extractive distillation using triethylene glycol as a selective solvent for diethylenetriamine.