C6-C16 Aliphatic Diol Refining via Alkali Neutralization
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Solution Overview
Problem
Current methods for refining C6-C16 aliphatic diols are inadequate in removing impurities like phenols, aliphatic mono-ols, esters, carboxylic acids, and hemiacetals, leading to increased impurity formation during distillation and equipment corrosion, resulting in low purity and high acidity in the final product.
Innovation Solution
The process involves distilling the crude C6-C16 aliphatic diol in the presence of an alkali metal compound and/or an alkaline earth metal compound, which neutralizes acids and inhibits the formation of additional impurities, allowing for efficient separation and recovery of a purified diol with reduced acidity and corrosion risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional distillation is used to purify crude C6-C16 aliphatic diol, then the diol can be separated from some impurities, but additional impurities are formed through cracking reactions and equipment corrosion occurs due to acidic impurities
Solution Approach 1:
The patent applies preliminary action by adding a base catalyst (such as sodium hydroxide, potassium hydroxide, or calcium oxide) to the crude diol before distillation begins. This preliminary treatment neutralizes acidic impurities and prevents cracking reactions from occurring during the subsequent distillation process, thereby preventing the formation of additional impurities and equipment corrosion while maintaining high product purity
Solution Approach 2:
The base catalyst acts as an intermediary substance that mediates between the acidic impurities and the distillation process. The catalyst neutralizes carboxylic acids and phenols to form salts, which then separate from the diol product during distillation. This intermediary approach allows the distillation to proceed without the harmful effects of acidic impurities while still achieving effective separation
2Manufacturing precision
If multiple distillation steps are performed to achieve high purity, then the purity of the diol product improves, but the complexity of the process and time required increase
Solution Approach 1:
By performing the base catalyst treatment as a preliminary step before a single distillation operation, the patent eliminates the need for multiple sequential distillation steps. The preliminary neutralization prevents impurity formation during distillation, allowing one distillation step to achieve the same purity that would otherwise require multiple steps, thereby reducing process complexity and time
Solution Approach 2:
The patent changes the chemical environment parameter by introducing a base catalyst, which alters the pH of the system. This parameter change transforms the distillation process from one that generates impurities through acid-catalyzed cracking to one that prevents impurity formation, enabling high purity to be achieved in fewer steps
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 significantly improves the purity of the C6-C16 aliphatic diol, achieving a total acidity of less than 500 ppm and reducing the number of distillation steps required, while minimizing equipment corrosion and maintaining the integrity of the diol product.
Implementation Method 1
the crude C6-C16 aliphatic diol is distilled in the presence of an alkali metal compound and/or an alkaline earth metal compound... which neutralizes acids
Implementation Method 2
distilling one or more times a crude C6-C16 aliphatic diol... under distillation conditions sufficient to obtain a purified C6-C16 aliphatic diol
Data Source
AI summary
A process of refining a crude C6-C16 aliphatic diol, preferably, a C6-C16 monocyclic aliphatic diol, more preferably, an isomeric mixture of cis/trans-(1,3)(1,4)-cyclohexanedimethanol, containing in addition to the diol one or more impurities selected from phenols, and aliphatic mono-ols, esters, carboxylic acids, and hemiacetals, and mixtures thereof. The refining process involves distilling the crude C6-C16 aliphatic diol in the presence of an alkali or alkaline earth metal compound, preferably, an excess thereof relative to acid equivalents present in the diol.