Aromatic Dianhydride Isolation via Sieve Tray Extraction
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Solution Overview
Problem
Current methods for producing aromatic dianhydrides result in decreased yields and increased by-product formation, limiting the efficiency of polyetherimide production.
Innovation Solution
A modified extraction procedure using a sieve tray extraction column at specific temperature and pressure conditions, optimizing the phthalic anhydride to aromatic bisimide molar ratio and solids content, to enhance dianhydride conversion and yield while minimizing imide anhydride by-products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional extraction methods are used to isolate aromatic dianhydride, then the extraction process can be performed with standard equipment, but the dianhydride conversion and yield are decreased while by-product formation increases
Solution Approach 1:
The patent applies parameter changes by optimizing the extraction temperature profile (first extraction at 60-160°C, second extraction at 140-200°C), residence time in the extraction column (0.5-5 minutes), and phase flow rates. These parameter optimizations enhance dianhydride conversion to 80% or more while reducing imide anhydride by-products to 2 weight percent or less, directly resolving the technical contradiction between productivity and harmful by-products
Solution Approach 2:
The patent introduces an extraction column as an intermediary device between the reaction system and final product isolation. This intermediary component enables selective separation of dianhydride from by-products through controlled liquid-liquid extraction, achieving high conversion efficiency while minimizing harmful by-product formation in the final product
2Manufacturing precision
If multiple extraction steps are used to improve purity, then by-product removal is enhanced, but the process complexity and time increase
Solution Approach 1:
The patent merges multiple extraction operations into a single integrated extraction column process. By combining first and second extraction steps in one continuous operation with optimized temperature and flow rate control, the system achieves high purity dianhydride (imide anhydride content of 2 weight percent or less) without requiring separate extraction units, thereby reducing device complexity while maintaining manufacturing precision
Solution Approach 2:
The patent implements continuous extraction action within the extraction column, maintaining optimal temperature and flow conditions throughout the process. This continuous operation ensures consistent high purity product output while eliminating the need for batch-wise multiple extraction steps, reducing both device complexity and process time
3Productivity
If extraction temperature is increased to improve extraction efficiency, then by-product removal is enhanced, but energy consumption and potential decomposition increase
Solution Approach 1:
The patent applies periodic action through a two-stage extraction temperature profile: first extraction at 60-160°C followed by second extraction at 140-200°C. This periodic temperature variation optimizes extraction efficiency at each stage while managing energy consumption, achieving high productivity without excessive energy input or product decomposition
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 increases overall dianhydride conversion and yield, reducing imide anhydride by-products and facilitating the production of high molecular weight poly(etherimide) with improved purity.
Implementation Method 1
removing the phthalimide from the aqueous reaction mixture by extracting the aqueous reaction mixture with an organic solvent using a single extraction column, wherein the extraction column is a sieve tray extraction column
Implementation Method 2
converting the aromatic tetraacid salt to the corresponding aromatic dianhydride
Data Source
AI summary
A method for producing an aromatic dianhydride includes reacting an aromatic diimide with a substituted or unsubstituted phthalic anhydride in an aqueous medium in the presence of an amine exchange catalyst to provide an aqueous reaction mixture including an N-substituted phthalimide, an aromatic tetraacid salt, and at least one of an aromatic triacid salt and an aromatic imide diacid salt. The method further includes removing the phthalimide from the aqueous reaction mixture by extracting the aqueous reaction mixture with an organic solvent using a sieve tray extraction column. The aromatic tetraacid salt is converted to the corresponding aromatic dianhydride. Aromatic dianhydrides prepared according to the method are also described.