Raman spectroscopy to improve process understanding and control of multi-phase slurry polymerization

Slurry polymerisation is a multi-phase (liquid, solid, and gas) mixture reaction that occurs very fast (within an hour), making it difficult to monitor in real time with a conventional technique in an ATEX environment. Raman spectroscopy was found to be very sensitive when monitoring inline during the course of the reaction. Not only could concentrations of propylene and polypropylene be quantified, but also low-level additions of H2, which is of particular interest for estimating the melt flow rate (MFR) governing the physico-chemical properties of the synthesised polymer. An Endress+Hauser Raman analyser equipped with a 532 nm wavelength laser allowed the acquisition of a broad spectral range for detecting all compounds of interest in the liquid, solid and gas phases.