Ionic Liquid Purification of Terephthalic Acid
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Solution Overview
Problem
Current processes for purifying crude terephthalic acid often require hydrogenation steps to reduce contaminant levels, particularly 4-carboxybenzaldehyde and para-toluic acid, which are costly and inefficient, failing to meet polymer-grade purity requirements.
Innovation Solution
Contacting crude terephthalic acid with an ionic liquid, such as imidazolium, pyridinium, or phosphonium-based solvents, under purifying conditions to selectively reduce contaminant concentrations, potentially including water and carboxylic acids like acetic acid, facilitating the extraction and dissolution of impurities without the need for hydrogenation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional purification processes are used to reduce contaminant levels in crude terephthalic acid, then hydrogenation steps are required to meet polymer-grade purity requirements, but this increases capital and operating costs
Solution Approach 1:
The patent changes the chemical parameters of the purification process by using ionic liquids with specific cations (imidazolium, pyridinium, phosphonium) and anions (acetate, carboxylate, halide) to selectively interact with contaminants. This parameter change enables purification without hydrogenation, reducing both capital and operating costs while achieving polymer-grade purity.
Solution Approach 2:
The ionic liquid acts as an intermediary substance that facilitates the separation of contaminants from terephthalic acid. The ionic liquid selectively dissolves or reacts with contaminants like 4-carboxybenzaldehyde and para-toluic acid, allowing them to be removed from the crude product without requiring hydrogenation steps.
2Manufacturing precision
If hydrogenation steps are used to reduce contaminant levels, then polymer-grade purity can be achieved, but the process becomes more complex and less efficient
Solution Approach 1:
The patent extracts contaminants from the crude terephthalic acid product using ionic liquids. The ionic liquid selectively interacts with and removes contaminants such as 4-carboxybenzaldehyde and para-toluic acid, separating them from the desired product without requiring complex hydrogenation equipment or multiple processing steps.
Solution Approach 2:
The patent replaces the mechanical/chemical hydrogenation system with a ionic liquid-based purification system. Instead of using hydrogen gas and catalysts in hydrogenation reactors, the process uses ionic liquids to selectively dissolve or react with contaminants, simplifying the equipment requirements and process mechanics.
3Manufacturing precision
If conventional purification methods are used, then some contaminant reduction is achieved, but 4-CBA content cannot be sufficiently reduced to meet polymer grade requirements
Solution Approach 1:
The patent changes the chemical selectivity parameters by choosing specific ionic liquids with particular cation-anion combinations. These ionic liquids have optimized interactions with 4-carboxybenzaldehyde and other contaminants, enabling consistent and reliable reduction of 4-CBA content to meet polymer-grade requirements that conventional methods cannot achieve.
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 lowers contaminant levels in crude terephthalic acid, achieving polymer-grade purity without hydrogenation, thereby reducing capital and operating costs and simplifying the purification process.
Implementation Method 1
contacting crude terephthalic acid with an ionic liquid to produce a terephthalic acid composition having a lower contaminant content
Implementation Method 2
facilitating the extraction and dissolution of impurities
Data Source
AI summary
A process for purifying crude terephthalic acid comprising a contaminant at a first concentration, the process comprising contacting the crude terephthalic acid with a solvent comprising an ionic liquid at purifying conditions to produce a solid terephthalic acid product having a second concentration of the contaminant lower than the first concentration.