Acrylic Acid Purification via Selective Extraction
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Solution Overview
Problem
Current purification processes for acrylic acid are plagued by polymerization tendencies and fouling issues due to high acetic acid concentrations, leading to frequent plant shutdowns, increased maintenance costs, and product losses.
Innovation Solution
A process involving the extraction of a mixture containing acrylic and acetic acid, followed by multistage distillation to separate and recirculate acetic acid, reducing its concentration and preventing polymerization, thereby eliminating the need for direct distillative separation and minimizing plant downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If acetic acid is separated by distillation to obtain high purity acetic acid, then acetic acid purity is improved, but polymerization of acrylic acid occurs and plant shutdowns are required
Solution Approach 1:
The patent applies extraction using a selective solvent to separate acetic acid from acrylic acid in the reaction mixture. The solvent selectively dissolves acetic acid, allowing it to be removed from the system without subjecting acrylic acid to high temperatures that would cause polymerization. This resolves the contradiction by achieving acetic acid separation through liquid-liquid extraction rather than thermal distillation.
Solution Approach 2:
The patent changes the separation parameter from thermal (distillation based on boiling point differences) to chemical (extraction based on solvent selectivity). By using a selective solvent that preferentially dissolves acetic acid, the separation occurs at ambient or mild temperatures, preventing acrylic acid polymerization while still achieving effective acetic acid removal.
2Productivity
If direct distillative separation is used to remove acetic acid, then separation efficiency is improved, but polymerization tendency increases and fouling occurs
Solution Approach 1:
The patent introduces a selective solvent as an intermediary substance to facilitate the separation of acetic acid from acrylic acid. The solvent acts as a mediator that selectively binds to acetic acid, enabling its removal without direct thermal contact between acrylic acid and the heating elements. This intermediary approach maintains high separation efficiency while eliminating the conditions that cause polymerization and fouling.
3Reliability
If acetic acid concentration is reduced through separation, then polymerization is prevented, but additional equipment and operating costs increase
Solution Approach 1:
The patent employs a selective solvent that naturally and selectively dissolves acetic acid from the reaction mixture without requiring additional energy input or complex equipment. The solvent's inherent selectivity performs the separation function automatically as the phases equilibrate, reducing the need for energy-intensive distillation equipment and associated operating costs while effectively preventing polymerization.
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 significantly extends plant operating times, reduces maintenance needs, and enhances acrylic acid purity and recovery, avoiding costly cleaning and disposal issues while maintaining high acetic acid removal efficiency.
Implementation Method 1
an extraction of a mixture containing acrylic acid and acetic acid is carried out
Implementation Method 2
a multistage distillation of the extract stream is carried out
Data Source
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AI summary
This invention relates to a process for the purification of acrylic acid from a mixture containing acrylic acid and acetic acid, comprising the following steps: i) extraction of the mixture containing acrylic acid and acetic acid with an extractant stream, whereby a raffinate stream and an extract stream are obtained, ii) distillation of the extract stream, whereby an acrylic acid stream and a return stream are obtained, characterized in that the return stream contains acetic acid and is recirculated into the extraction. Furthermore, the invention comprises a plant for carrying out this process.