Oxidation Process for Purified Aromatic Carboxylic Acids
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Solution Overview
Problem
The production of purified aromatic carboxylic acids, such as terephthalic acid, is hindered by significant 'burning' during oxidation processes, leading to high costs and inefficiencies in purification steps due to the presence of impurities like 4-carboxybenzaldehyde.
Innovation Solution
A multi-step oxidation process is employed, where the aromatic feedstock is initially oxidized under conditions to minimize burning, followed by further oxidation with an oxygen source and catalysts like Ru, Au, or Pt to reduce impurities, allowing for subsequent purification to achieve high purity aromatic carboxylic acids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-pressure exothermic oxidation is used to produce crude aromatic carboxylic acid, then production efficiency is improved, but burning increases leading to higher byproduct formation and purification costs
Solution Approach 1:
The oxidation process is divided into multiple sequential steps with different catalysts and conditions. The first step uses a Co-Mn-Br catalyst at high temperature and pressure to achieve high conversion, while subsequent steps use different catalysts (e.g., Pd, Pt, or biocatalysts) under milder conditions to selectively remove impurities without excessive burning. This segmentation allows each step to be optimized for its specific function, resolving the contradiction between productivity and harmful byproduct formation.
Solution Approach 2:
The patent changes key reaction parameters between steps: temperature is reduced from high-pressure conditions to milder conditions, pressure is adjusted, and catalyst composition is modified. These parameter changes allow the process to achieve high productivity in the first step while minimizing burning and byproduct formation in subsequent steps, directly addressing the technical contradiction.
2Manufacturing precision
If oxidation conditions are intensified to reduce impurities, then product purity is improved, but burning increases leading to higher costs
Solution Approach 1:
The purification process is segmented into multiple steps, each targeting specific impurities with specialized catalysts. This allows impurity removal to be achieved through cumulative effect of multiple mild steps rather than one intense step, thereby improving product purity without proportionally increasing burning and material loss.
Solution Approach 2:
The patent introduces intermediate purification steps with specific catalysts that act as mediators to selectively convert particular impurities. These intermediaries enable targeted impurity removal without requiring overall intensification of oxidation conditions, thus improving purity while minimizing burning.
3Manufacturing precision
If multiple purification steps are added to remove impurities, then product purity is improved, but process complexity increases
Solution Approach 1:
The patent combines multiple purification functions into an integrated multi-step process where each step serves both purification and preparation for the next step. By merging the oxidation and purification operations into a coordinated sequence with shared process infrastructure, the overall complexity is managed while achieving high product purity.
4Loss of substance
If burning is reduced in the initial oxidation step, then reactant material loss is decreased, but impurity levels may increase requiring more intensive purification
Solution Approach 1:
The process segments the oxidation into steps with different objectives: the first step prioritizes high conversion with acceptable impurity levels, while subsequent steps prioritize impurity removal. This segmentation allows reactant material loss to be minimized in the first step while impurity removal is handled in dedicated subsequent steps, resolving the contradiction between material loss and crude product purity.
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 reduces the severity of oxidation reactions, decreases byproduct formation, and lowers overall production costs by minimizing burning and impurities, enabling the production of high-purity aromatic carboxylic acids with reduced operational burdens.
Implementation Method 1
further oxidation with an oxygen source and catalysts like Ru, Au, or Pt to reduce impurities
Implementation Method 2
An aqueous mixture including the crude aromatic carboxylic acid reaction product resulting from this initial oxidation step is then further oxidized through exposure to an oxygen source in the presence of an oxidation catalyst
Data Source
AI summary
A process including: (a) contacting an aqueous solution including a crude aromatic carboxylic acid with an oxygen source in the presence of an oxidation catalyst including at least one of Ru, Au, Pt, Ir or V, and oxides, alloys, salts and mixtures thereof; and (b) purifying the product of step (a) to form a purified aromatic carboxylic acid.