Laurolactam Purification via Integrated Crystallization and Distillation
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Solution Overview
Problem
Conventional methods for purifying laurolactam involve multistage distillation under reduced pressure, leading to thermal stress and partial decomposition, resulting in reduced yield and high production costs.
Innovation Solution
A process integrating distillation and crystallization, where the laurolactam synthesis stream is cooled to exceed the solubility limit, allowing selective crystallization of laurolactam, followed by multistage distillation of the mother liquor to recover solvents and reactants, reducing thermal stress and the number of separation steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multistage distillation under reduced pressure is used to purify laurolactam, then separation of components with different boiling points is achieved, but thermal stress causes partial decomposition and reduces yield
Solution Approach 1:
The patent performs preliminary crystallization of laurolactam from the reaction mixture before distillation. By cooling the mixture to crystallize laurolactam first, the main product is separated from the thermal stress of distillation, preserving yield while still achieving purification through subsequent mild distillation of the mother liquor
Solution Approach 2:
The patent exploits the phase transition of laurolactam from liquid to crystal through cooling. This crystallization step separates laurolactam from components with different phase behaviors, enabling purification without subjecting the product to high-temperature distillation that causes decomposition
2Manufacturing precision
If multistage distillation is used to remove all components, then complete separation is achieved, but the number of thermal separation steps increases production cost
Solution Approach 1:
The patent segments the purification process into two distinct stages: (1) crystallization to remove laurolactam and most solids from the reaction mixture, and (2) simplified distillation to process only the mother liquor. This segmentation reduces the burden on the distillation system and lowers overall production cost
Solution Approach 2:
The patent extracts laurolactam from the complex reaction mixture through crystallization before distillation. By removing the main product early in the form of crystals, the subsequent distillation only needs to handle the mother liquor containing impurities, simplifying the separation process and reducing costs
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 achieves early removal of laurolactam with minimal thermal stress, recovering over 90% of valuable materials and maintaining high purity (>99%) while reducing thermal decomposition and production costs.
Implementation Method 1
cooling the synthesis process stream comprising laurolactam, a mother liquor, synthesis starting materials and low, mid- and high boiling fractions to a temperature wherein only the solubility limit of the laurolactam is exceeded, to selectively crystallize the laurolactam from the mother liquor
Implementation Method 2
decompressing the heated synthesis process stream in a flash vessel to obtain a vapor phase and a low-boiling fraction which comprises laurolactam
Implementation Method 3
sending the vapor phase to a distillative separating sequence to produce a fraction of the vapor phase comprising laurolactam
Data Source
AI summary
A process for purifying laurolactam by means of integrated connection of distillation and crystallization is provided. The crystallization is performed as a solution or melt crystallization. The process reduces thermal stress applied to the laurolactam stream and improved yields are obtained. Raw materials are recovered and recycled in the production sequence.