(38b) Real Time Measurement of Propylene Oxide in Polyether Polyols Via Calorimetry

Shell Chemicals is among the leading global producers of polyether polyols. CARADOL polyether polyols, when combined with isocyanates, are used in urethane applications. Urethanes find use in products such as flexible and rigid foams, and in Coatings, Adhesives, Sealants & Elastomer (CASE) systems. As a result we may encounter them in a wide variety of goods including furniture, car seating, bedding, paints and coatings, artificial sports tracks, playground surfaces, ski suits and other waterproof leisure wear. Shell produces more than four hundred thousand metric tons per year of polyether polyols.

Polyether polyols are produced by base or acid catalyzed polymerization of propylene Oxide (PO) with polyhydric alcohols and/or other functional initiators. An important aspect of safeguarding these exothermic reactions is to maintain a safe solution concentration of PO. Knowing exactly how much PO is in solution is difficult to ascertain due to the physical properties of the reacting mixture. Grab samples are hazardous to collect and difficult to analyze. In situ Infrared (IR) spectroscopy can readily detect the PO in solution, but how to calibrate the resulting IR spectra? We have accomplished this through reaction calorimetry. By adding pulses of PO to the reacting mixture and back integration across the pulse of the heat released, we can estimate the concentration of PO at any given time in the reaction. This is matched to the corresponding IR spectra to create calibration sets for the various grades. This work will also discuss moving these calibrations across platforms with different probes and detectors.