MEG and 1,2-BDO Separation via Reduced-Pressure Distillation
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Solution Overview
Problem
Current methods for separating monoethylene glycol (MEG) and 1,2-butanediol (1,2-BDO) from their mixture are inefficient due to similar boiling points and the formation of a homogeneous minimum boiling azeotrope, leading to high energy costs and product degradation during distillation.
Innovation Solution
A process involving a single distillation column where MEG and 1,2-BDO are separated by operating within specific temperature and pressure ranges, allowing for the removal of an MEG stream and an azeotrope of MEG and 1,2-BDO as an overhead stream, with further processing steps to enhance MEG recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fractional distillation is used to separate MEG and 1,2-BDO, then separation of glycols is achieved, but the process requires high energy consumption and leads to product degradation due to high temperatures
Solution Approach 1:
The patent changes the operating parameters of distillation from conventional high temperature and atmospheric pressure to low temperature (120-190°C) and reduced pressure (5 kPa to atmospheric pressure). This parameter change enables separation of MEG and 1,2-BDO while avoiding thermal degradation and reducing energy consumption significantly
Solution Approach 2:
The patent applies a preliminary concentration step before distillation to increase the MEG:1,2-BDO ratio to at least 10:1. This preliminary action simplifies the subsequent distillation process by reducing the complexity of separating close-boiling components, thereby lowering overall energy requirements
2Manufacturing precision
If repeated heating at raised temperatures is applied in distillation steps, then water is removed from glycols, but decomposition of the desired glycol products occurs
Solution Approach 1:
The patent employs reduced pressure distillation at temperatures between 120-190°C, significantly lower than conventional distillation temperatures. This parameter change prevents thermal decomposition of MEG and 1,2-BDO while still enabling effective separation and water removal
Solution Approach 2:
The patent introduces a vacuum environment as an intermediary condition that enables water removal at lower temperatures. The reduced pressure acts as a mediator that allows volatile components to be removed without requiring high thermal energy input that would cause decomposition
3Ease of operation
If azeotropic distillation with an azeotrope-forming agent is used to separate MEG and 1,2-BDO, then separation is facilitated, but further process steps are required to remove the azeotrope forming agents
Solution Approach 1:
The patent extracts or removes the azeotrope-forming agent (water) from the system through preliminary concentration and controlled distillation steps. By removing water before the main separation process, the patent eliminates the need for additional steps to remove azeotrope-forming agents, simplifying the overall process
Solution Approach 2:
The patent performs preliminary concentration to remove water and achieve a MEG:1,2-BDO ratio of at least 10:1 before conducting the main distillation separation. This preliminary action prevents azeotrope formation issues during the separation process, eliminating the need for additional removal steps
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 achieves high recovery and purity of MEG with minimal energy consumption and avoids product degradation, effectively separating MEG from 1,2-BDO in a weight ratio of at least 10:1, even from reaction product streams derived from hydrogenolysis of saccharides.
Implementation Method 1
a distillation column wherein an azeotrope of a small amount of the MEG present with the 1,2-BDO is removed as an overhead stream
Implementation Method 2
the formation of a homogeneous minimum boiling azeotrope between MEG and 1,2-BDO at atmospheric pressure
Data Source
AI summary
The invention provides a process for the separation of MEG and 1,2-BDO from a first mixture comprising MEG and 1,2-BDO in a weight ratio of at least 10:1 (MEG:1,2-BDO), said process comprising the steps of; (i) providing the first mixture as a feed to a distillation column at a point in the range of from 20 to 80% of the column height; (ii) operating the distillation at a temperature in the range of from 120 to 190° C. and at a pressure in the range of from 5 kPa to atmospheric pressure; (iii) removing an MEG stream from the distillation column at a point below the point at which the first mixture is fed; (iv) removing an overheads stream comprising an azeotrope of MEG and 1,2-BDO.