Enrichment Feed Process for PTA Purification
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Solution Overview
Problem
The production of purified terephthalic acid (PTA) is costly due to the need for extensive purification of the oxidizer mother liquor stream, which contains impurities and by-products from the oxidation of p-xylene, and existing methods for impurity removal are inefficient and costly.
Innovation Solution
A process involving the formation of an enrichment feed by concentrating a solvent-rich stream and recycling it to the PTA production process, allowing for the enrichment of specific compounds such as isophthalic acid and phthalic acid, which reduces the need for subsequent purification steps and minimizes the concentration of impurities in the PTA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If extensive purification of the oxidizer mother liquor stream is performed to remove impurities and by-products, then the purity of PTA is improved, but the manufacturing cost increases
Solution Approach 1:
The invention applies preliminary action by adding isophthalic acid and/or phthalic acid to the oxidizer mother liquor stream before the purification process. This pre-enrichment step modifies the impurity profile in advance, allowing for more efficient removal of specific compounds during subsequent purification stages, thereby achieving high PTA purity while reducing overall manufacturing costs
Solution Approach 2:
The invention changes the compositional parameters of the mother liquor stream by introducing specific carboxylic acid compounds (isophthalic acid and/or phthalic acid) in controlled amounts. This parameter modification enables optimization of the purification process by creating a more favorable impurity distribution that can be removed more efficiently, reducing the complexity and cost of achieving target purity levels
2Manufacturing precision
If conventional purification methods are used to remove impurities from the oxidizer mother liquor stream, then the concentration of impurities in PTA is reduced, but the productivity decreases due to extensive purification steps
Solution Approach 1:
By pre-adding isophthalic acid and/or phthalic acid to the mother liquor stream, the invention creates an optimized impurity profile before purification begins. This preliminary modification allows subsequent purification steps to remove impurities more rapidly and efficiently, reducing the number and duration of purification stages required while achieving the same final purity level, thus maintaining high productivity
3Adaptability or versatility
If the oxidizer mother liquor stream is recycled to the oxidation reactor, then the use of catalyst and promoter is optimized, but the concentration of impurities accumulates in the recycle stream
Solution Approach 1:
The invention modifies the compositional parameters of the recycle stream by introducing isophthalic acid and/or phthalic acid in specific concentrations. This parameter change creates an enriched feed composition that maintains catalyst and promoter effectiveness while establishing a controlled impurity profile that can be more effectively managed during purification, preventing uncontrolled accumulation of harmful substances
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 process enhances the yield of PTA by reducing the amount of impurities and by-products in the oxidizer mother liquor stream, thereby decreasing manufacturing costs and improving the efficiency of PTA production.
Implementation Method 1
subjecting a solvent rich stream to a solids concentration zone to form a concentrated solvent rich stream
Implementation Method 2
subjecting the concentrated solvent rich stream to a concentrated SLS zone to form a mother liquor stream and an enrichment feed; wherein the concentrated SLS zone comprises at least one solid liquid separation device
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A process is provided for producing an enriched carboxylic acid compositions produced by contacting composition comprising a carboxylic acid with an enrichment feed in an enrichment zone to form an enriched carboxylic acid composition. This invention also relates to a process and the resulting compositions for removing catalyst from a carboxylic acid composition to produce a post catalyst removal composition.