Diphenylmethane Diamine Isomer Control via Parameter Adjustment
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Solution Overview
Problem
Existing processes for producing di- and polyamines of the diphenylmethane series face challenges in efficiently changing the isomer distribution during load changes, leading to operational issues such as increased by-product formation and difficulties in maintaining product quality and production capacity.
Innovation Solution
Adjusting the molar ratios of aniline to formaldehyde and acid catalyst, as well as reaction temperature, allows for complete rearrangement reactions while minimizing by-product formation, enabling targeted changes in the isomer distribution of 2,4'-MDA during load changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If production capacity is changed, then output quantity is adjusted, but residence time changes导致rearrangement reaction completeness deteriorates and by-product formation increases
Solution Approach 1:
The patent adjusts reaction parameters (temperature, molar ratios of aniline to formaldehyde and acid catalyst) to compensate for residence time changes during load variations. By dynamically modifying these parameters, the process maintains complete rearrangement reaction and controlled isomer composition even when production capacity changes, preventing by-product formation that would otherwise occur due to insufficient residence time.
2Manufacturing precision
If molar ratios are adjusted to change isomer distribution, then product composition is optimized, but reaction conditions become more complex
Solution Approach 1:
The patent employs systematic adjustment of molar ratios (aniline to formaldehyde and acid catalyst to aniline) as controllable parameters to achieve desired isomer distributions. By establishing clear parameter relationships and adjustment rules, the process enables precise control of isomer composition (particularly 2,4'-MDA content) without requiring overly complex control systems, as the parameter changes follow defined patterns based on production requirements.
3Reliability
If residence time is extended to ensure complete rearrangement, then reaction completeness is improved, but production capacity decreases
Solution Approach 1:
The patent compensates for reduced residence time at higher production capacities by adjusting temperature and molar ratios. This allows the process to maintain complete rearrangement reaction and desired isomer composition even with shorter residence times, thereby enabling higher production capacities without sacrificing reaction completeness or product quality.
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 ensures optimal economic, ecological, and operational viability by maintaining high yield and quality of the di- and polyamines, reducing procedural problems like caking or blockages, and allowing quick adjustments to product composition demands.
Implementation Method 1
condensation of aniline and formaldehyde followed by acid-catalyzed rearrangement
Implementation Method 2
acid-catalyzed rearrangement at different production capacities
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
The invention relates to a method for producing diamines and polyamines of the diphenylmethane series, by condensing aniline and formaldehyde followed by an acid-catalysed rearrangement at different production capacities with alteration of the isomer composition in the resulting diamines of the diphenylmethane series (altering the 2,4'-MDA content). Adapting the molar ratios of the total used aniline to the total used formaldehyde and of the total used acid catalyst to the total used aniline, and adapting the reaction temperature, allows the rearrangement reaction to be fully completed despite the change in dwell time inevitably associated with a change in production capacity, and allows the formation of undesired by-products to be avoided as far as possible; the intended modification to binuclear content is likewise achieved.