On-Line Monitoring of Chlorosilane Streams by Raman Spectroscopy

Abstract

On-line Raman spectroscopy was used to monitor the composition of methylchlorosilane streams from distillation columns. A spectrometer was assembled that used 532 nm laser light and a fiberoptic probe that could be inserted into corrosive liquid streams. The spectral regions below 800 cm−1 and near 2250 cm−1 contained strong, distinctive bands that were used to identify and quantitate the species of interest. On-line spectra were recorded at 5 min sampling intervals. Several instances were found where large changes in the composition of the columns were observed. Detection limits of 1000 ppm were generally achievable, and, in favorable circumstances, compositional changes of 100 ppm could be detected. Raman spectroscopy gave much better time resolution than current gas chromatography (GC) monitoring and is also projected to have lower capital and maintenance costs.