Styrene Purification via Static and Dynamic Crystallization
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Solution Overview
Problem
Current methods for purifying styrene from naphtha cracked pyrolysis gasoline are energy intensive and inefficient in removing impurities like color inducing species, sulfur species, and alpha-methylstyrene, which affect polymer properties and require complex equipment to prevent unwanted polymerization.
Innovation Solution
A method involving crystallization stages, including static and dynamic crystallization, effectively removes impurities with higher melting points than styrene, such as color inducing species, oxygenates, and sulfur species, from styrene compositions, achieving high purity without the need for additional complex treatment steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If extractive distillation is used to remove close boiling molecules, then energy consumption is reduced, but impurities such as chromophores, sulfur, and oxygenates remain in the styrene
Solution Approach 1:
The purification process is divided into two distinct stages: first extractive distillation to remove close-boiling molecules (ethylbenzene, xylene), then crystallization to remove impurities with higher melting points (chromophores, sulfur compounds, oxygenates). This segmentation allows each stage to target specific impurity types, achieving comprehensive purification without excessive energy consumption.
Solution Approach 2:
The method changes the purification approach by utilizing melting point differences rather than solely relying on boiling point differences. By cooling the styrene to temperatures below its melting point (30.6°C), impurities with higher melting points are left in the liquid phase while pure styrene crystallizes, enabling removal of sulfur and oxygenate impurities that distillation cannot effectively remove.
2Manufacturing precision
If chemical treatment or adsorbent treatment is used to remove impurities, then styrene purity is improved, but unwanted polymerization occurs and equipment complexity increases
Solution Approach 1:
The crystallization process is a self-service purification method that relies on the natural phase change behavior of styrene and its impurities. By controlling temperature to enable crystallization, the system automatically separates pure styrene crystals from impurity-rich mother liquor without requiring external chemical agents or complex equipment, thus avoiding polymerization issues and reducing operational complexity.
3Manufacturing precision
If normal distillation is used to remove close boiling molecules, then separation is achieved, but energy consumption increases
Solution Approach 1:
An extractive solvent acts as an intermediary substance that selectively interacts with close-boiling molecules (ethylbenzene, xylene) based on their different solubility characteristics. This allows separation from the styrene phase without requiring the high energy input of normal distillation, as the solvent mediates the separation process through selective extraction rather than thermal energy input.
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 allows for the cost-efficient production of high-purity styrene by completely or substantially removing impurities, reducing energy consumption and equipment complexity, and preventing polymer formation, thereby improving polymer properties and process efficiency.
Implementation Method 1
subjecting the crude composition to at least one crystallization step, wherein the at least one crystallization step comprises at least one of a static crystallization stage and a dynamic crystallization stage
Data Source
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AI summary
The present invention relates to a method for preparing a purified styrene composition, wherein the method comprises providing a crude composition containing 70% by weight or more styrene based on the total weight of the crude composition and subjecting the crude composition to at least one crystallization step, wherein the at least one crystallization step comprises at least one of a static crystallization stage and a dynamic crystallization stage, and wherein the crude composition contains one or more impurities selected from the group consisting color inducing species, oxygenates, sulfur species, alpha-methylstyrene and arbitrary combinations of two or more thereof.