Diphenylmethane Diamine Production Capacity Adjustment
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Solution Overview
Problem
Existing processes for producing di- and polyamines of the diphenylmethane series face challenges in maintaining product composition consistency when changes in production capacity occur, leading to unwanted changes in product composition and increased by-product formation due to altered residence times.
Innovation Solution
Adjusting the molar ratios of aniline to formaldehyde and acidic catalyst to total aniline during changes in load, while maintaining consistent reactor temperatures, ensures the rearrangement reaction runs to completion and minimizes changes in product composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If production capacity is changed, then productivity is improved, but product composition consistency deteriorates due to altered residence times
Solution Approach 1:
The patent applies parameter changes by adjusting the molar ratios of reactants (aniline to formaldehyde) and catalyst (acidic catalyst to aniline) in response to production capacity changes. When production capacity increases, the patent specifies increasing the aniline to formaldehyde molar ratio and the acidic catalyst to aniline molar ratio to compensate for reduced residence time, thereby maintaining product composition consistency across different production rates
Solution Approach 2:
The patent implements dynamics by making the molar ratios of reactants and catalyst dynamic rather than fixed. The molar ratios are adjusted based on the production capacity level, allowing the process to adapt to different operating conditions while maintaining consistent product composition. This dynamic adjustment ensures that the rearrangement reaction runs to completion regardless of residence time variations
2Productivity
If residence time is reduced to increase production capacity, then productivity is improved, but by-product formation increases
Solution Approach 1:
The patent uses parameter changes to prevent by-product formation during high-capacity operation. By increasing the molar ratio of aniline to formaldehyde and the molar ratio of acidic catalyst to aniline when production capacity is increased, the patent ensures that the rearrangement reaction completes fully even with reduced residence time, thereby preventing the formation of unwanted by-products
Solution Approach 2:
The patent applies preliminary anti-action by pre-adjusting the molar ratios of reactants and catalyst before the rearrangement reaction occurs at reduced residence time. This proactive adjustment prevents by-product formation rather than correcting it afterward, ensuring that the reaction proceeds to completion under all production capacity conditions
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 allows for seamless changes in production load without affecting the quality of the di- and polyamines, reducing by-product formation and maintaining high productivity and product consistency.
Implementation Method 1
In the absence of an acidic catalyst, formaldehyde is first condensed with aniline to give what is called aminal, with elimination of water
Implementation Method 2
This is followed by the acid-catalyzed rearrangement to MDA in a first step to give para- or ortho-aminobenzylaniline
Implementation Method 3
The aminobenzylanilines are converted to MDA in a second step
Data Source
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. Adapting the respective molar ratios of the total used aniline to the total used formaldehyde and of the total used acid catalyst to the total used aniline allows the rearrangement reaction to be fully completed despite the change in dwell time inevitably associated with a change in production capacity and ensures that no undesired fundamental changes occur in the product composition.