Polyol Ester Production via Acid Fraction Recycling
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Solution Overview
Problem
The production of polyol esters, particularly G-esters, using ethylene oxide is hazardous and non-selective, leading to the formation of mixtures with different chain lengths and requiring extensive safety measures, whereas direct esterification processes face challenges in maintaining acid quality with increasing reuse, affecting the color and stability of the final product.
Innovation Solution
A process involving the partial recycling of aliphatic monocarboxylic acid, where the acid is separated into fractions: a first cut containing coloring components, a second cut for nearly pure acid recycling, and a third cut for contaminated acid removal, allowing for efficient reuse of the intermediate fraction to maintain acid quality and color stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct esterification with acid recycling is used, then production cost is reduced and productivity is improved, but acid quality deteriorates and color stability worsens
Solution Approach 1:
The acid recycling process is segmented into multiple cuts (first cut, second cut, third cut) based on color quality. The first cut removes highly colored acid, the second cut recycles intermediate quality acid, and the third cut removes heavily colored acid. This segmentation allows selective recycling of acid fractions that maintain color stability while improving overall production efficiency.
Solution Approach 2:
Different portions of the recycled acid are treated differently based on their local quality characteristics. The intermediate quality acid from the second cut is recycled for continued use, while the highly colored acid from the first and third cuts is discarded or used for non-critical applications. This local quality approach optimizes both productivity and color stability.
2Loss of substance
If complete acid recycling is implemented, then loss of substance is reduced, but manufacturing precision deteriorates due to color contamination
Solution Approach 1:
The process selectively discards the highly colored acid fractions from the first and third cuts, while recovering and recycling the intermediate quality acid from the second cut. This selective discarding and recovering approach minimizes acid loss while maintaining product purity and color stability.
Solution Approach 2:
The recycling strategy changes based on the color parameter of the acid fraction. By monitoring color quality and adjusting the recycling decision accordingly, the process optimizes the balance between acid utilization and product quality, reducing unnecessary recycling of contaminated acid while minimizing waste.
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 enables the production of polyol esters with excellent color number and stability by concentrating coloring components in a small portion of the excess acid, allowing for frequent reuse of the less contaminated acid fraction, thus improving the efficiency and quality of the esterification process.
Implementation Method 1
the aliphatic monocarboxylic acid used also forms an azeotrope with water under the reaction conditions and can act as an entraining agent to remove the water of reaction
Implementation Method 2
the water of reaction formed is distilled off from the reaction vessel together with the excess monocarboxylic acid and passed into a downstream phase separator in which the monocarboxylic acid and water separate depending on their solubility properties
Data Source
AI summary
The present invention relates to a process for the production of polyol esters by reacting polyols with linear or branched aliphatic monocarboxylic acids having 3 to 20 carbon atoms by partially recycling the separated aliphatic monocarboxylic acid into the esterification reaction or into subsequent esterification reactions.