MGDN Crystallization via Controlled Cooling Rate

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Solution Overview

Problem

The existing processes for isolating methylglycinenitrile-N,N-diacetonitrile (MGDN) from aqueous crude mixtures face challenges due to its high temperature-dependent solubility, leading to inefficient crystallization and contamination issues, as well as encrustation in crystallizers.

Innovation Solution

A process involving slow cooling of the aqueous emulsion from above the solidification point to below it, with a controlled cooling rate of ≤5 K/h, followed by further cooling and/or concentration, to separate the solidification of emulsified MGDN from its crystallization from solution, thereby preventing the formation of fines and encrustation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If cooling crystallization is used to isolate MGDN from aqueous solution, then MGDN can be separated from the solution, but fine needle-like crystals form which agglomerate and incorporate mother liquor, resulting in dark brown moist crystals with impurities

Engineering Contradiction:

Improvecrystal purityVSAvoidcrystallization efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent changes the cooling rate parameter from rapid cooling to slow cooling (≤5 K/h) to fundamentally alter the crystallization process. This parameter change prevents the formation of fine needle-like crystals and their agglomeration, allowing MGDN to crystallize as larger, purer crystals without incorporating mother liquor, thus resolving the contradiction between crystal purity and crystallization efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements a two-stage cooling process with distinct phases: first stage cooling from above to below the solidification point at slow rate, then second stage cooling at greater rate. This periodic action separates the solidification of emulsified MGDN from crystallization from solution, preventing encrustation and fine crystal formation while maintaining high yield and purity

Inventive Principle:

Principle #19Periodic action

2Productivity

If cooling rate is increased to improve crystallization speed, then crystallization efficiency increases, but encrustation occurs on crystallizer walls and fine crystals form

Engineering Contradiction:

Improvecrystallization speedVSAvoidencrustation and fine crystal formation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent performs preliminary action by first cooling the emulsion to below the solidification point at a slow rate (≤5 K/h) before initiating rapid cooling. This preliminary slow cooling stage allows emulsified MGDN to solidify completely first, preventing subsequent encrustation and fine crystal formation when rapid cooling occurs, thus resolving the contradiction between crystallization speed and harmful effects

Inventive Principle:

Principle #10Preliminary action

3Productivity

If rapid cooling is used to isolate MGDN quickly, then isolation speed increases, but mother liquor is incorporated into crystals and purity decreases

Engineering Contradiction:

Improveisolation speedVSAvoidcrystal purity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent segments the cooling process into two distinct stages: first stage cooling at slow rate (≤5 K/h) to below solidification point, second stage cooling at greater rate. This segmentation separates the solidification of emulsified MGDN from the crystallization step, allowing rapid isolation in the second stage while maintaining high purity by preventing mother liquor incorporation in the first stage, thus resolving the contradiction between isolation speed and purity

Inventive Principle:

Principle #1Segmentation

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 method results in larger, cleaner MGDN crystals with reduced mother liquor adherence, simplifying purification and preventing crystallizer encrustation, while maintaining high MGDN yields and purity.

Implementation Method 1

the aqueous emulsion is, starting from a temperature above the solidification point, cooled to a temperature below the solidification point, the cooling rate averaged over time not exceeding 5 K/h, until substantially the entirety of the emulsified MGDN has solidified

Methodology Applied

Scientific EffectSolidification: Freezing

Implementation Method 2

the resulting aqueous suspension is cooled further and/or concentrated, and the cooling rate may be greater than in step (a)

Methodology Applied

Scientific EffectCooling: Cooling

Data Source

PatentUS7754911B2Method for isolating methyl glycine nitrile-N,N-diacetonitriles from an aqueous crude mixture

Publication Date: 2010.07.13 BASF SE

AI summary

The invention relates to a process for isolating methylglycinenitrile-N,N-diacetonitrile (MGDN) from an aqueous emulsion which comprises MGDN and has an MGDN content of 3-50% by weight in a crystallizer, comprising the steps:(a) the aqueous emulsion is, starting from a temperature above the solidification point, cooled to a temperature below the solidification point, the cooling rate averaged over time not exceeding 5 K/h, until substantially the entirety of the emulsified MGDN has solidified,(b) the resulting aqueous suspension is cooled further and/or concentrated, and the cooling rate may be greater than in step (a).