Dynamic VLE-Coupled Kinetic Modeling of Bulk Propylene Polymerization, Calibrated via Reactor Pressure Decay

Abstract

This work presents a dynamic, model-based kinetic measurement method that couples vapor-liquid-equilibrium with reaction kinetics for the bulk-phase polymerization of propylene in a bench-scale reactor. This model couples Peng-Robinson‑based flash calculations with a simplified kinetic scheme (activation, propagation, deactivation). Reactor pressure-time trajectories from polymerizations (at 20°C–30°C) are used as model input. The novelty of this approach lies in explicitly embedding vapor-liquid equilibrium into the dynamic pressure‑based calibration of polymerization kinetics under bulk pre‑polymerization conditions. Through the process of parameter tuning, the simulated and measured reactor pressure drop caused by conversion of liquid propylene to polypropylene in a multi-component mixture are aligned, yielding the simulated polymerization rate and the elementary reaction rate constants. The model reproduces the characteristic pressure decrease and end-point yields within acceptable deviations and demonstrates instantaneous catalyst activity profiles, the activity decay over reaction time, and the temperature response of the catalyst. This approach enables access to detailed catalytic polymerization kinetics of propylene at mild temperatures which are typically used under industrial pre-polymerization reactors.