Methylenebis(Cyclohexylamine) Distillation Using a Dividing-Wall Column
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Solution Overview
Problem
Existing processes for producing methylenebis(cyclohexylamine) face issues such as high exposure to high temperatures, prolonged residence times, and crystallization problems during distillation, leading to reduced operating times and increased complexity, while also failing to maintain a consistent isomer ratio.
Innovation Solution
A process involving catalytic hydrogenation of MDA followed by distillation using a dividing-wall column to reduce exposure to high temperatures and residence time, and prevent crystallization, while maintaining a constant isomer ratio, utilizing catalysts like nickel, cobalt, palladium, platinum, ruthenium, and rhodium, and employing a continuous reactor system with controlled temperature and residence time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional distillation is used to purify methylenebis(cyclohexylamine), then purification is achieved, but exposure to high temperatures and prolonged residence times cause crystallization problems and reduced operating times
Solution Approach 1:
The distillation process is segmented into two separate columns: a first distillation column for initial purification and a second distillation column for final purification. This segmentation allows each column to operate under optimized conditions, reducing the overall exposure to high temperatures and preventing crystallization problems that occur in single-stage distillation.
Solution Approach 2:
The patent introduces an intermediary stream between the two distillation columns. The side stream from the first column serves as feed to the second column, acting as an intermediary that allows progressive purification at controlled temperature stages, avoiding the need for single high-temperature exposure that causes crystallization.
2Manufacturing precision
If conventional distillation is used, then purification is achieved, but residence time is prolonged leading to reduced operating times and increased complexity
Solution Approach 1:
By dividing the distillation process into two columns with different functions, the residence time in each column is optimized for its specific purpose. The first column handles bulk separation quickly, while the second column performs fine purification, reducing total residence time compared to a single prolonged distillation process.
Solution Approach 2:
The first distillation column performs preliminary purification before the second column. This preliminary action removes the bulk of impurities first, so the second column only needs to handle minor purification, significantly reducing the total time required for complete purification.
3Manufacturing precision
If conventional distillation is used, then purification is achieved, but operating complexity and device complexity increase
Solution Approach 1:
The distillation system is segmented into two specialized columns rather than one complex column. Each column is simpler in design and operation, handling specific separation tasks, which reduces overall operational complexity compared to managing a single complex distillation system with multiple functions.
4Manufacturing precision
If conventional distillation is used, then purification is achieved, but energy consumption increases
Solution Approach 1:
The first distillation column performs preliminary separation of major components, removing the bulk of impurities before the second column. This preliminary action reduces the energy burden on the second column, as it only needs to handle minor purification of a already partially purified stream, thereby reducing total energy consumption.
Solution Approach 2:
By segmenting the distillation into two columns with different separation tasks, each column can be optimized for its specific function, improving energy efficiency. The first column handles high-volume low-difficulty separation, while the second handles low-volume high-difficulty separation, optimizing overall energy use compared to a single column attempting all separations.
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 a high purity methylenebis(cyclohexylamine) with a consistent isomer ratio, reducing energy consumption and minimizing crystallization, thereby improving operational efficiency and product quality.
Implementation Method 1
catalytic hydrogenation of MDA
Implementation Method 2
distillation using a dividing-wall column
Data Source
AI summary
The present invention provides a process for producing methylenebis(cyclohexylamine), comprising the steps of 1) catalytically hydrogenating MDA, 2) removing the catalyst and 3) subsequently distilling the product of the hydrogenation, in which at least one dividing-wall column is used in step 3). Exposure to high temperature and residence time of the product is reduced and problems due to crystallization do not occur. The methylenebis(cyclohexylamine) isomer ratio also may remain largely constant during the distillation.