Inline Raman Spectroscopy of an Emulsion Copolymerization in an Industrial Pilot Plant Using Indirect Hard Modeling

Abstract

Raman spectroscopy is used to determine the concentrations of monomers and polymers in the second stage of a twostage emulsion polymerization process. The indirect hard modeling (IHM) approach is applied to monitor inline the reaction in semi-batch operation in lab scale and pilot scale. This method requires the spectra of all pure components. While the pure spectra of water and monomers are easily measured as pure components, the spectra of two different copolymers are constructed from reaction spectral data containing mixtures. Good predictive capabilities of the developed model are demonstrated.

Polymer Colloids: Current Challenges, Emerging Applications, and New Developments

“…Gas chromatography (GC) − and spectroscopic techniques such as near-infrared spectroscopy (NIRS), , nuclear magnetic resonance (NMR), − ion mobility, and Raman spectroscopy − have all been used for the direct on-line monitoring of the free monomer in emulsion polymerization. Among these techniques, Raman spectroscopy is the best suited spectroscopic technique for monitoring the individual free monomer concentration in an in-line process, with successful examples on monitoring and on-line control of copolymer composition reported for emulsion polymerization including its implementation in an industrial pilot plant . Reaction calorimetry has also been successfully implemented to monitor the free monomer concentration in homopolymerizations in which the heat of the reaction, which is proportional to the rate of the polymerization, is measured .…”

“…For example, copolymer composition, monomer conversion, and polymerization rate can be estimated from direct measurement of the free monomers in the reactor and can be manipulated by altering the monomer/initiator feed. Gas chromatography (GC) − and spectroscopic techniques such as near-infrared spectroscopy (NIRS), , nuclear magnetic resonance (NMR), − ion mobility, and Raman spectroscopy − have all been used for the direct on-line monitoring of the free monomer in emulsion polymerization. Among these techniques, Raman spectroscopy is the best suited spectroscopic technique for monitoring the individual free monomer concentration in an in-line process, with successful examples on monitoring and on-line control of copolymer composition reported for emulsion polymerization including its implementation in an industrial pilot plant .…”

“…Among these techniques, Raman spectroscopy is the best suited spectroscopic technique for monitoring the individual free monomer concentration in an in-line process, with successful examples on monitoring 70 and on-line control of copolymer composition reported for emulsion polymerization including its implementation in an industrial pilot plant. 71 Reaction calorimetry has also been successfully implemented to monitor the free monomer concentration in homopolymerizations in which the heat of the reaction, which is proportional to the rate of the polymerization, is measured. 72 In the case of copolymerization, the individual free monomers are nonobservable but can be estimated reliably using the Mayo− Lewis equation as a soft sensor.…”