Diamine Synthesis via Absorption Recycling
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Solution Overview
Problem
Current processes for producing dimethylaminopropylamine (DMAPA) face inefficiencies due to low yield, excessive reagent consumption, and high production costs, particularly due to the low boiling point of dimethylamine, which requires costly distillation for recycling, and struggle with by-product formation and purification.
Innovation Solution
A continuous process involving the reaction of dimethylamine with acrylonitrile, where dimethylamine is introduced in excess, with recycling facilitated through an absorption system, followed by hydrogenation in the presence of alkali metal hydroxide and a catalyst, and subsequent separation and distillation to achieve high purity DMAPA, utilizing a system that includes reactors, absorption, and distillation columns to manage reactant recycling and by-product separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dimethylamine is introduced in excess to improve reaction yield, then the yield of aminonitrile increases, but the complexity of recycling unreacted dimethylamine increases due to its low boiling point requiring distillation
Solution Approach 1:
The patent introduces an absorption system as an intermediary between the reactor and recycling process. The absorption system uses a suitable solvent to absorb unreacted dimethylamine from the reaction mixture, converting the difficult distillation problem into a simpler absorption-desorption process. This mediator enables efficient recycling without requiring complex distillation facilities.
Solution Approach 2:
The patent changes the physical-chemical parameters of the recycling process by using absorption instead of distillation. By selecting appropriate absorption conditions (temperature, pressure, solvent type), the process transforms the separation mechanism from thermal distillation to chemical/physical absorption, thereby simplifying the recycling facility while maintaining high recovery efficiency.
2Loss of substance
If distillation is implemented to recycle unreacted dimethylamine, then recycling is achieved, but the production facilities become significantly heavier and manufacturing costs increase
Solution Approach 1:
The absorption system serves as an intermediary that replaces the heavy and expensive distillation equipment. By using a liquid absorbent to capture dimethylamine, the process avoids the need for large distillation columns, condensers, and associated heavy infrastructure, thereby reducing both facility weight and manufacturing cost.
Solution Approach 2:
The patent employs a relatively simple and inexpensive absorption system that can be easily replaced or regenerated compared to complex distillation facilities. The absorption solvent can be regenerated and reused, creating a cost-effective recycling solution that avoids heavy capital investment in permanent distillation infrastructure.
3Manufacturing precision
If traditional purification methods are used for diamine, then purification is achieved, but the purity is insufficient and by-products are difficult to separate
Solution Approach 1:
The patent introduces a selective complexing agent as an intermediary in the purification process. This agent forms selective complexes with specific by-products or impurities, enabling their easy separation from the desired diamine product. The complexing agent acts as a mediator that enhances the ease of separation while achieving high purity.
Solution Approach 2:
The purification process utilizes parameter changes such as pH adjustment, temperature variation, or solvent composition changes to selectively precipitate or separate by-products from the diamine. By controlling these parameters, the process achieves both high purity and ease of manufacture.
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 process achieves high yield and purity (>99.5%) of DMAPA, reduces by-product formation, facilitates reagent recycling, and lowers production costs by eliminating the need for extensive distillation, while maintaining selectivity and controlling reaction heat.
Implementation Method 1
a second fraction is sent to an absorption system to allow solubilization of excess monoamine; the excess monoamine in gaseous form which is sent to said absorption system which allows its solubilization
Implementation Method 2
The recycling of the monoamine uses a separation system, which makes it possible to recover: on the one hand, the aminonitrile, of which a first fraction is sent to a reactor for stage (b) and a second fraction is sent to a absorption system
Implementation Method 3
separation of the alkali metal hydroxide by evaporation of the diamine obtained in step (b) and of the water; distillation of the diamine
Implementation Method 4
a condensation of the DMA vapors obtained, which significantly weighs down the production facilities
Data Source
AI summary
The present invention relates to a continuous method (P) for preparing diamine, including: reacting the corresponding alkene nitrile with the corresponding monoamine in order to form the corresponding aminonitrile, the monoamine being introduced in molecular excess with respect to the alkene nitrile, wherein the unreacted monoamine is recirculated to the reaction; followed by reducing the aminonitrile produced by hydrogen in the presence of at least one alkali-metal hydroxide, water, and a hydrogenation catalyst; and purifying the diamine.