Enriched Carboxylic Acid Process for Terephthalic Purity

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Solution Overview

Problem

The production of purified terephthalic acid is hindered by the accumulation of impurities in the oxidizer mother liquor stream during the oxidation of p-xylene, leading to increased manufacturing costs and reduced yield, as existing purification methods are inefficient in removing these impurities.

Innovation Solution

A process involving the oxidation of an aromatic feedstock to form a crude carboxylic acid composition, followed by crystallization, cooling, and enrichment in a catalyst removal zone, with an optional enrichment feed in an enrichment zone to produce an enriched composition, effectively removing impurities and maximizing the concentration of valuable compounds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional purification methods are used to remove impurities from the oxidizer mother liquor stream, then the purity of terephthalic acid is improved, but the manufacturing cost increases and yield decreases

Engineering Contradiction:

Improvepurity of terephthalic acidVSAvoidyield and manufacturing cost

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The invention performs preliminary oxidation in a first oxidation zone to convert impurities like p-toluic acid and 4-carboxybenzaldehyde to terephthalic acid before the main purification process. This preliminary action reduces the burden on subsequent purification steps and minimizes impurity accumulation in the mother liquor stream, thereby improving overall yield without sacrificing purity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes oxidation parameters by conducting two-stage oxidation at different conditions. The first oxidation zone operates with specific temperature, pressure, and catalyst conditions to selectively convert impurities, while the second oxidation zone completes the oxidation of p-xylene. This parameter differentiation allows efficient impurity removal while maintaining high terephthalic acid yield

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the concentration of impurities in the oxidizer mother liquor stream is minimized through aggressive purification, then the quality of purified terephthalic acid is improved, but the manufacturing cost increases

Engineering Contradiction:

Improvequality of purified terephthalic acidVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention converts the harmful impurities in the mother liquor stream into beneficial products by performing a second oxidation on the mother liquor to convert remaining impurities like p-toluic acid and 4-carboxybenzaldehyde into additional terephthalic acid. This transforms waste streams into valuable product, improving quality while reducing manufacturing cost through resource utilization

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Stability of the object's composition

If impurities are removed from the oxidizer mother liquor stream through conventional means, then the accumulation of inert compounds is reduced, but the process complexity and cost increase

Engineering Contradiction:

Improveaccumulation of inert compoundsVSAvoidprocess complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The invention implements continuous oxidation of the oxidizer mother liquor stream in a second oxidation zone, continuously converting impurities to terephthalic acid rather than periodic or batch treatment. This continuous action prevents accumulation of inert compounds like isophthalic acid and benzoic acid without requiring complex intermittent purification equipment, maintaining process simplicity while ensuring composition stability

Inventive Principle:

Principle #20Continuity of useful action

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 purified terephthalic acid by efficiently removing impurities, reducing the need for costly purification methods and allowing for the retention or addition of specific compounds, thereby improving the production efficiency and flexibility of the terephthalic acid process.

Implementation Method 1

oxidizing an aromatic feedstock in a primary oxidation zone to form a crude carboxylic acid composition

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

crystallizing said slurry composition or said crude carboxylic acid composition in a crystallization zone to form a crystallized slurry composition

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 3

cooling and optionally enriching said crystallized slurry composition in a cooling zone to form a cooled carboxylic acid composition

Methodology Applied

Scientific EffectCooling: Cooling

Data Source

PatentEP1881953B1A process to produce an enriched carboxylic acid composition

Publication Date: 2017.10.25 GRUPO PETROTEMEX SA DE CV

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.