Polycarbonate Depolymerization With In-Line Raman End-Point Control
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Solution Overview
Problem
Current chemical recycling methods for polycarbonate-based resins face challenges such as the use of harmful chemicals, high temperature and pressure requirements, low yield, and inefficiencies in large-scale reactions, making it difficult to achieve high-purity aromatic diol compounds.
Innovation Solution
A method involving real-time monitoring of Raman spectra during the depolymerization of polycarbonate-based resins using an in-line analyzer to optimize reaction conditions, allowing for the recovery of high-purity aromatic diol compounds by adjusting the reaction end point and minimizing by-products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If chemical decomposition of polycarbonate is performed using conventional methods (thermal decomposition, hydrolysis, or alcohol decomposition), then aromatic diol compounds can be obtained, but the process requires high temperature and pressure conditions, uses harmful chemicals, and achieves low yield
Solution Approach 1:
The patent introduces an in-line Raman analyzer as an intermediary monitoring system that provides real-time feedback on the depolymerization reaction progress. This enables precise control of reaction conditions, allowing the use of milder conditions while maintaining high yield by optimizing the reaction endpoint based on real-time spectral data rather than conventional fixed-time or fixed-temperature protocols
Solution Approach 2:
The patent implements real-time monitoring of Raman spectra to dynamically adjust reaction parameters (temperature, pressure, reaction time) during the depolymerization process. By continuously measuring the concentration of aromatic diol compounds and adjusting conditions based on spectral data, the process achieves high yield under milder conditions compared to conventional fixed-parameter methods
2Productivity
If the reaction scale is increased from laboratory level to industrial level (tens of liters), then production efficiency improves, but the conversion rate and reaction behavior differ from laboratory scale, leading to reduced manufacturing precision
Solution Approach 1:
The patent implements a feedback control system using in-line Raman spectroscopy to monitor the depolymerization reaction in real-time during the reaction process. The Raman spectral data provides continuous feedback on the concentration of aromatic diol compounds, enabling dynamic adjustment of reaction conditions to maintain optimal conversion rates even at industrial scale (tens of liters), thereby resolving the scale-up effect that causes deviation from laboratory-level performance
Solution Approach 2:
The patent replaces conventional offline analytical methods (HPLC, NMR) and manual sampling with an in-line Raman spectroscopic system that provides real-time, non-invasive monitoring directly in the reactor. This substitution enables continuous process control at industrial scale without the sampling delays and analysis time required by traditional methods, maintaining manufacturing precision across different scales
3Measurement precision
If conventional analysis methods (HPLC or NMR) are used to monitor reaction progress, then product purity can be confirmed, but the analysis time and complexity increase, reducing productivity
Solution Approach 1:
The patent replaces offline HPLC or NMR analysis with an in-line Raman spectroscopic system that provides real-time monitoring of the depolymerization reaction. The Raman analyzer directly measures the concentration of aromatic diol compounds in the reaction mixture without requiring sample extraction, preparation, or lengthy analysis, thereby maintaining measurement precision while dramatically improving monitoring efficiency and productivity
Solution Approach 2:
The patent implements continuous real-time monitoring of the depolymerization reaction using in-line Raman spectroscopy throughout the entire reaction process. This continuous measurement capability eliminates the intermittent sampling and batch analysis required by HPLC or NMR methods, providing uninterrupted feedback on product formation and enabling immediate optimization of reaction conditions, thereby maintaining high productivity without compromising measurement precision
Data Source
AI summary
The present disclosure relates to a preparation method of a monomer composition for synthesizing recycled plastic, the method comprising the steps of: subjecting a polycarbonate-based resin to a depolymerization reaction in the presence of an alcohol; monitoring a Raman spectrum of an aromatic diol compound obtained from the depolymerization reaction or alcohol in a reactor through which depolymerization reaction proceeds; and recovering the aromatic diol compound, and to a preparation device of a monomer composition for synthesizing recycled plastic, and a monomer composition for synthesizing recycled plastic, a recycled plastic and a molded product using the same.