Caprolactam Purification Without Organic Solvents

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Solution Overview

Problem

The traditional process for purifying caprolactam requires complex equipment and involves the use of organic solvents, which poses environmental and safety hazards, and is costly and laborious to manage.

Innovation Solution

A process using direct contact with alkaline compounds of polyvalent metals to treat crude caprolactam solutions, eliminating the need for organic solvents, reducing equipment complexity, and simplifying operations by using bivalent or trivalent metal hydroxides or oxides to precipitate and separate byproducts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If organic solvent extraction is used to purify caprolactam, then purification effectiveness is improved, but environmental safety and operational safety deteriorate due to solvent hazards

Engineering Contradiction:

Improvepurification effectivenessVSAvoidenvironmental and safety hazards

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The invention extracts and removes the harmful organic solvents from the purification process entirely, replacing them with water-based extraction methods. This eliminates the harmful factors while maintaining purification effectiveness through alternative separation mechanisms using water-soluble substances.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the fundamental parameter of the extraction medium from organic solvents to water-based solutions. By altering the chemical nature of the extraction phase from hydrophobic to hydrophilic, the process eliminates safety and environmental hazards while achieving purification through different solubility characteristics.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If traditional double extraction process is used, then caprolactam purification is achieved, but device complexity and operational complexity increase

Engineering Contradiction:

Improvecaprolactam purificationVSAvoidequipment and process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention merges the multiple extraction steps into a simplified single-stage or reduced-stage process. By combining the functions of multiple extraction columns and solvent recovery systems into a more integrated water-based extraction system, the device complexity is reduced while maintaining purification effectiveness.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The invention replaces expensive, complex solvent recovery and distillation equipment with simpler water-based extraction equipment. Water being inexpensive and non-flammable allows for simpler safety systems and reduced equipment requirements, effectively using a 'disposable' approach to solvent management where water can be easily replaced and treated.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Productivity

If organic solvents are used for extraction, then caprolactam separation efficiency is improved, but operational costs and environmental costs increase

Engineering Contradiction:

Improveseparation efficiencyVSAvoidoperational and environmental costs

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The invention converts the potential harm of using large volumes of water into a benefit by utilizing water's unique properties: high heat capacity for energy-efficient heating and cooling, high dielectric constant for selective solubility, and environmental benignity. The abundant, inexpensive water replaces costly organic solvents, turning a seemingly disadvantageous choice into an economically and environmentally superior solution.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The invention changes the extraction medium parameter from organic solvents to water, fundamentally altering the thermodynamic and economic parameters of the process. Water's lower cost, higher safety margin, and easier treatability transform the operational cost structure while maintaining separation efficiency through optimized water-based extraction conditions.

Inventive Principle:

Principle #35Parameter changes

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 purified caprolactam with reduced environmental impact, lower operational costs, and simpler facility design, while ensuring safety and efficiency in the purification of caprolactam without the need for solvent extraction.

Implementation Method 1

treating the solution of crude caprolactam by means of direct contact with one or more alkaline compounds of polyvalent metals... so as to thus obtain a suspension... separating the solids from the suspension of step (ii) to obtain an aqueous solution of crude caprolactam

Methodology Applied

Scientific EffectPrecipitation: Precipitation

Data Source

PatentUS11208380B2Process for the purification of caprolactam from a solution of crude caprolactam without organic solvent extraction

Publication Date: 2021.12.28 AQUAFILSLO D O O

AI summary

The present invention relates to a process for purifying caprolactam from solutions of crude caprolactam by a direct treatment with one or more alkaline compounds of polyvalent metals, preferably bivalent and trivalent, without resorting to organic solvent extraction as used in the usual purification process.A further subject of the present invention is a facility devoid of a unit for organic solvent extraction and designed to carry out the caprolactam purification process described herein.