Adipic Acid Nitrate Removal via Thermal Gas Treatment
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Solution Overview
Problem
Adipic acid produced from the oxidation of KA oil with nitric acid often contains residual nitrate compounds, which degrade the quality of polymers like polyamides, necessitating the removal of these impurities to enhance polymer quality.
Innovation Solution
Contacting solid adipic acid with a gas at elevated temperatures between 85°C to 95°C, potentially followed by a second step at temperatures above 95°C but below 100°C, effectively removes nitrate compounds, reducing their concentration from 2.0 to less than 1.8 ppm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional crystallization and solid-liquid separation are used for adipic acid purification, then the adipic acid can be recovered and purified from the reaction mixture, but nitrate compounds remain as residual impurities affecting polymer quality
Solution Approach 1:
The patent applies parameter changes by conducting gas-phase treatment at specific temperature ranges (85-95°C or 95-100°C) to remove nitrate compounds from solid adipic acid. This thermal treatment modifies the physical and chemical parameters of the system to selectively eliminate nitrate impurities while preserving the adipic acid product, thereby resolving the contradiction between purification quality and nitrate residue removal.
2Reliability
If the adipic acid is dried at higher temperatures to remove more nitrate compounds, then nitrate removal efficiency improves, but the risk of adipic acid decomposition and energy consumption increase
Solution Approach 1:
The patent optimizes the temperature parameter within specific ranges (85-95°C or 95-100°C) to achieve effective nitrate removal while preventing adipic acid decomposition. By carefully controlling this critical parameter, the process maximizes nitrate removal efficiency while maintaining product integrity and minimizing energy consumption.
3Reliability
If multiple high-temperature drying steps are applied to remove nitrate compounds, then nitrate removal improves, but process complexity and energy consumption increase
Solution Approach 1:
The patent segments the drying process into distinct temperature stages (first stage at 85-95°C, optionally followed by a second stage at 95-100°C). This segmented approach allows effective nitrate removal through controlled thermal treatment while simplifying the overall process design and reducing energy consumption compared to continuous high-temperature drying.
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 significantly reduces nitrate content in adipic acid to below 1.8 ppm, improving the quality of polymers by eliminating impurities, and can be conducted in a fluidized bed using heat exchangers with oxygen-depleted air as the gas.
Implementation Method 1
contacting the adipic acid with a gas at an elevated temperature... removing at least part of nitrate compounds from solid adipic acid
Data Source
AI summary
The present invention relates to a method of removing nitrate compounds from solid adipic acid.