Terephthalic Acid Production via Bubble Column Reactor
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Solution Overview
Problem
Prior art processes for producing purified terephthalic acid (PTA) without intermediate liquor exchange between primary oxidation and oxidative digestion stages face challenges such as increased carbon burn losses, inability to use recycled solvent, and the need for additional purification systems to control contaminant levels, making them commercially unviable.
Innovation Solution
A process that minimizes carbon burn during oxidative digestion by optimizing the primary oxidation stage to produce a purer initial slurry, which is then processed without the need for liquor exchange, using a bubble column reactor with specific agitation and feed distribution configurations to enhance oxygen solubility and mass transfer, thereby reducing impurity formation and solvent burn.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If liquor exchange is performed between primary oxidation and oxidative digestion stages, then catalyst concentration is reduced and carbon burn losses are minimized, but process complexity and equipment cost increase due to the need for additional separation equipment
Solution Approach 1:
The patent extracts and removes the harmful catalyst compounds from the liquid phase through liquor exchange between oxidation stages. By separating the catalyst-containing mother liquor and replacing it with fresh solvent, the system eliminates the negative effect of catalyst accumulation on carbon burn losses while maintaining process efficiency.
Solution Approach 2:
The patent discards the spent mother liquor containing accumulated catalyst compounds and recovers the valuable TPA product. The liquor exchange process allows continuous removal of harmful catalysts while recovering and purifying the TPA, balancing waste removal with resource recovery.
2Device complexity
If liquor exchange is eliminated between primary oxidation and oxidative digestion stages, then process complexity is reduced, but carbon burn losses increase due to accumulated catalyst concentrations
Solution Approach 1:
The patent implements continuous liquor exchange between primary oxidation and oxidative digestion stages, ensuring continuous removal of catalyst compounds. This continuous action prevents catalyst accumulation and maintains optimal reaction conditions throughout the process, eliminating carbon burn losses while keeping the process design relatively simple.
3Manufacturing precision
If primary oxidation is optimized to produce purer initial slurry, then impurity formation is reduced and liquor exchange may be eliminated, but oxidation reaction efficiency must be significantly enhanced
Solution Approach 1:
The patent optimizes multiple parameters of the primary oxidation process including temperature, pressure, catalyst composition, and oxygen supply conditions. By carefully adjusting these parameters, the system achieves high TPA purity in the initial slurry, reducing the need for subsequent liquor exchange while maintaining high oxidation efficiency.
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
The process achieves efficient production of purified terephthalic acid with reduced carbon burn losses and eliminates the need for expensive liquor exchange steps, enabling the use of recycled solvent and improving product quality and operational efficiency.
Implementation Method 1
a bubble column reactor with specific agitation and feed distribution configurations to enhance oxygen solubility and mass transfer
Implementation Method 2
a bubble column reactor with specific agitation and feed distribution configurations to enhance oxygen solubility and mass transfer
Implementation Method 3
para-xylene is oxidized to produce a crude terephthalic acid
Implementation Method 4
a dialkyl aromatic compound (e.g., para-xylene) is oxidized to produce a crude terephthalic acid
Implementation Method 5
the dissolution and reprecipitation associated with oxidative digestion partitions a portion of the relatively unreactive aromatic impurities (e.g. isophthalic acid (IPA)) out of the solid phase and into the liquid phase
Implementation Method 6
the dissolution and reprecipitation associated with oxidative digestion partitions a portion of the relatively unreactive aromatic impurities (e.g. isophthalic acid (IPA)) out of the solid phase and into the liquid phase
Data Source
Figure 1
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AI summary
Disclosed is an optimized system for more efficiently and economically producing terephthalic acid. A solvent purification system is employed to remove of at least one aromatic impurity present in a solvent purification feed. At least about 20 weight percent of the solvent purification feed originates from a cooled, post-digestion, TPA-containing slurry.