Unsupervised crystallization monitoring with NIR Spatially Resolved Spectroscopy combined with Principal Component Analysis

• Published in: Journal of crystal growth 2023-09, Vol.618, p.127329, Article 127329
• Main Authors: Kersaudy, R., Gagnière, E., Caillol, N., Colson, D., Valour, J.P., Mangin, D.
• Format: Article
• Language: English
• Subjects: A1. Secondary nucleation; A2. In situ monitoring; A2. Industrial crystallization; A2. Seed crystals; B3. Principal Component Analysis; B3. Spatially Resolved Spectroscopy; Chemical and Process Engineering; Engineering Sciences
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2023.127329

•In situ monitoring of crystallization with Spatially Resolved Spectroscopy.•Analysis of the score trajectories of Principal Components.•Impact of impurities on the trajectory of the scores recorded in batch crystallizations.•Detection of secondary nucleation thanks to SRS probe. ATR-FTIR and NIR spectroscopies are widely deployed to monitor the liquid phase composition during crystallization. However, information about the solid phase is also essential for the crystallization process control. We propose in this study to implement Spatially Resolved Spectroscopy (SRS) based on the near-infrared spectral range, to collect relevant data related to both physical and chemical aspects of suspensions during seeded cooling crystallizations of an industrial organic compound. Different batch crystallizations with varying experimental conditions were carried out and monitored. Principal Component Analysis (PCA) was applied and score trajectories were analyzed over time. This data mining method enabled to differentiate batches according to their initial composition and to detect a secondary nucleation mechanism.