Cyclohexanedicarboxylic Acid Crystallization Without Salt Purification
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Solution Overview
Problem
Existing methods for producing 1,4-cyclohexanedicarboxylic acid derivatives require additional steps to handle by-produced salts and purification, leading to inefficiencies and lower purity.
Innovation Solution
A method involving the heat concentration of an aqueous ammonia solution of 1,4-cyclohexanedicarboxylic acid to precipitate the derivative as a crystal, avoiding salt production and unnecessary purification steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cyclohexane is oxidized with air using a cobalt salt catalyst, then 1,4-cyclohexanedicarboxylic acid can be produced, but the reaction requires high temperature (200°C or higher) and high pressure (30 atm or higher) conditions
Solution Approach 1:
The patent changes the chemical parameters of the reaction system by introducing a specific organic carboxylic acid modifier (acetic acid, propionic acid, or butyric acid) in combination with cobalt salt catalyst. This parameter modification allows the reaction to proceed at lower temperatures (100-200°C) and pressures (10-30 atm) while maintaining high productivity and selectivity for 1,4-cyclohexanedicarboxylic acid production.
2Productivity
If cyclohexane is oxidized with air using a cobalt salt catalyst, then 1,4-cyclohexanedicarboxylic acid can be produced, but the reaction requires high pressure (30 atm or higher) conditions
Solution Approach 1:
The patent modifies the reaction pressure parameter by using a modified cobalt catalyst system with organic carboxylic acid. This catalyst modification enables the reaction to achieve high productivity at reduced pressures (10-30 atm) compared to conventional methods requiring 30 atm or higher, while maintaining safe and controllable reaction conditions.
3Productivity
If cobalt catalyst is used for oxidation, then reaction activity is improved, but cobalt compounds are toxic and expensive
Solution Approach 1:
The patent introduces organic carboxylic acid (acetic acid, propionic acid, or butyric acid) as an intermediary substance that modifies the cobalt catalyst system. This intermediary enhances the catalytic activity and selectivity of cobalt, allowing reduced cobalt loading while maintaining high reaction activity. The carboxylic acid modifier also improves the environmental compatibility and reduces the toxic impact of cobalt compounds.
Solution Approach 2:
The patent changes the catalytic system parameters by combining cobalt salt with specific organic carboxylic acid modifiers. This parameter optimization reduces the required cobalt concentration while maintaining or enhancing reaction activity, thereby reducing the harmful effects associated with cobalt toxicity and cost.
4Productivity
If conventional oxidation methods are used, then 1,4-cyclohexanedicarboxylic acid can be produced, but the process involves complex multi-step procedures including isolation and purification
Solution Approach 1:
The patent enables continuous oxidation of cyclohexane to 1,4-cyclohexanedicarboxylic acid using the modified cobalt catalyst system with organic carboxylic acid. The reaction proceeds continuously under optimized conditions (100-200°C, 10-30 atm) with high selectivity, eliminating the need for complex isolation and purification steps. The modified catalyst maintains stable activity throughout continuous operation, simplifying the overall process.
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 approach enhances production efficiency by eliminating salt-handling steps and achieving high-purity 1,4-cyclohexanedicarboxylic acid, which improves the yield of subsequent products like 1,4-dicyanocyclohexane and 1,4-bis(aminomethyl)cyclohexane.
Implementation Method 1
oxidation with air using a cobalt salt catalyst
Data Source
AI summary
A production method for a 1,4-cyclohexanedicarboxylic acid derivative, having a step of subjecting an aqueous ammonia solution of 1,4-cyclohexanedicarboxylic acid to heat concentration, thereby precipitating a 1,4-cyclohexanedicarboxylic acid derivative as a crystal.