Acetonitrile Separation from Waste Streams via Dehydration
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Solution Overview
Problem
Conventional acetonitrile separation processes struggle to effectively isolate acetonitrile from industrial waste streams containing impurities like methanol, water, allyl alcohol, and oxazole due to azeotrope formation and similar vapor pressures, leading to reduced separation efficiencies and lower product purities.
Innovation Solution
A process involving dehydration of the feedstock stream to reduce water content, followed by a reactor reaction with a strong acid to convert allyl alcohol and oxazole into higher-boiling protonated salt species or oxazole sulfate, combined with subsequent distillation steps to yield high-purity acetonitrile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional distillation schemes are used to separate acetonitrile from waste streams containing water, methanol, allyl alcohol, and oxazole, then acetonitrile recovery is attempted, but separation efficiency is reduced due to azeotrope formation and similar vapor pressures
Solution Approach 1:
The patent applies preliminary action by removing water from the waste stream before the distillation process. The waste stream is treated to reduce water content to less than 1 wt%, which prevents azeotrope formation between water and acetonitrile during distillation. This preliminary dehydration step enables subsequent distillation to achieve high acetonitrile purity (greater than 98 wt%) that would otherwise be unattainable due to azeotropic limitations.
Solution Approach 2:
The patent changes the physical-chemical parameters of the waste stream by modifying water content through dehydration. By reducing water concentration from typical high levels to less than 1 wt%, the vapor pressure relationships between components are altered, eliminating the azeotropic barrier and enabling effective separation of acetonitrile from remaining impurities through distillation.
2Manufacturing precision
If multiple distillation zones at varying pressures are used to recover acetonitrile, then some separation is achieved, but the process becomes complex and cannot effectively handle additional impurities like methanol, water, allyl alcohol, and oxazole
Solution Approach 1:
The patent simplifies the separation process by performing water removal as a preliminary action before distillation. This dehydration step consolidates what would otherwise require multiple complex distillation zones, reducing the overall process complexity while maintaining the ability to handle multiple impurities including methanol, allyl alcohol, and oxazole.
Solution Approach 2:
The patent extracts water from the waste stream through dehydration before the main distillation process. This extraction of the most problematic impurity (water) simplifies the subsequent distillation by removing the component that causes azeotrope formation, thereby reducing device complexity while maintaining high separation efficiency.
3Productivity
If conventional separation schemes are applied to waste streams with high water content, then the process is simpler, but azeotrope formation prevents achieving high acetonitrile purity
Solution Approach 1:
The patent performs preliminary dehydration to remove water before distillation, which prevents azeotrope formation during the separation process. This enables the system to achieve high acetonitrile purity (greater than 98 wt%) while maintaining relatively simple process equipment and operations, resolving the contradiction between process simplicity and product purity.
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
The process significantly improves acetonitrile purity and yield by effectively removing impurities, enhancing the efficiency of downstream separation operations and reducing associated costs.
Implementation Method 1
the dehydrating of the feedstock stream includes distilling the feedstock stream in a dehydration distillation column to yield a dehydration distillate stream and a dehydration bottoms stream
Implementation Method 2
the dehydration distillation column is operated at a pressure less than 85 kPa
Implementation Method 3
reacting ally alcohol from the dehydrated stream with a strong acid in a reactor to yield a reactor output stream
Implementation Method 4
subsequent distillation steps to yield high-purity acetonitrile
Data Source
AI summary
Provided herein are processes for the separation of acetonitrile from low-purity feedstock streams. The provided processes are particularly useful for isolating acetonitrile at high purity from chemical manufacturing waste streams that include methanol, water, and allyl alcohol.