Lewis Base Addition to Control Emulsion in Liquid-Liquid Extraction
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Solution Overview
Problem
The recovery of diphosphonite-containing compounds from hydrocyanation reaction product mixtures is hindered by the formation of emulsion phases and rag layers in multistage countercurrent liquid-liquid extractors, which impede phase separation and catalyst extraction efficiency.
Innovation Solution
The process involves adding a Lewis base, such as anhydrous ammonia, pyridine, or alkylamine, to the mixing section of the multistage countercurrent liquid-liquid extractor to enhance settling and reduce the size of emulsion phases, thereby improving the extraction of diphosphonite-containing compounds into the light phase and preventing rag layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multistage countercurrent liquid-liquid extraction is used to recover diphosphonite-containing compounds, then extraction efficiency is improved, but emulsion phase formation and rag layer accumulation occur which impede phase separation
Solution Approach 1:
A Lewis base (such as ammonia, amine, or pyridine) is introduced as an intermediary substance to modify the interaction between the heavy phase and light phase. The Lewis base complexes with the Lewis acid catalyst in the heavy phase, reducing the catalyst's ability to stabilize emulsions and promote rag layer formation. This intermediary agent facilitates cleaner phase separation while maintaining extraction efficiency.
Solution Approach 2:
The chemical environment in the mixing section is modified by changing the concentration and type of Lewis base added. This parameter change alters the complexation equilibrium between Lewis acid and Lewis base, thereby controlling the extent to which the catalyst is deactivated and its emulsion-stabilizing ability is reduced, optimizing phase separation without compromising extraction performance.
2Productivity
If extended continuous extraction is performed to improve recovery, then more diphosphonite compounds are extracted, but interfacial rag layer accumulates and halts phase separation
Solution Approach 1:
The Lewis base is added preliminarily to the mixing section before phase separation occurs in the settling section. This preliminary action prevents the formation of stable rag layers at the interface by deactivating the Lewis acid catalyst that would otherwise promote rag formation during extended extraction operations, enabling continuous uninterrupted operation.
Solution Approach 2:
The Lewis acid catalyst, which causes harmful rag layer formation and emulsion stabilization, is converted into a beneficial complex with the Lewis base. This complexation reduces the catalyst's harmful emulsion-stabilizing properties while maintaining its catalytic function, thereby converting the source of the problem into a solution that enables continuous operation.
3Reliability
If Lewis base is added to complex with Lewis acid, then rag layer formation is reduced, but extraction efficiency may be affected
Solution Approach 1:
The Lewis base is added specifically to the mixing section where the heavy and light phases are contacted, rather than uniformly throughout the entire extraction system. This localized addition ensures that the Lewis acid is complexed at the interface where emulsion formation occurs, improving phase separation without significantly affecting the overall extraction equilibrium and efficiency.
Solution Approach 2:
A controlled, partial amount of Lewis base is added to achieve sufficient complexation of the Lewis acid catalyst to prevent rag layer formation, without adding excessive amounts that would disrupt the extraction equilibrium. The dosage is optimized to provide just enough deactivation of the catalyst's emulsion-stabilizing ability while maintaining extraction efficiency.
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
The addition of a Lewis base increases the rate of settling and the amount of diphosphonite-containing compounds in the light phase, reduces the size and formation rate of rag layers, and enhances the overall extraction efficiency of diphosphonite compounds, preventing process shutdowns due to rag accumulation.
Implementation Method 1
a Lewis base is added to the mixing section of the first stage of the multistage countercurrent liquid-liquid extractor... wherein the heavy phase comprises organic mononitriles, organic dinitriles and a complex of said Lewis acid and said Lewis base
Implementation Method 2
a light phase separates from a heavy phase in the settling section
Data Source
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AI summary
Disclosed herein are methods for recovering diphosphonite-containing compounds from mixtures comprising organic mononitriles and organic dinitriles, using liquid-liquid extraction. Also disclosed are treatments to enhance extractability of the diphosphonite-containing compounds.