Mathematical Model and Parameter Estimation for Gas-Phase Ethylene Homopolymerization with Supported Metallocene Catalyst

A dynamic model for gas-phase ethylene homopolymerization using a supported metallocene catalyst is developed in this work. A single-site model was first developed, with model parameters estimated from measurements from 11 experimental runs in a semibatch laboratory-scale reactor. Estimability analysis techniques were applied to aid in the parameter estimation. Although the single-site model provided good fits for both the polymerization rate and hydrogen concentration, it failed to accurately predict the molecular weight data and its distribution. Sequentially, a simplified two-site model was built to improve model predictions. The two-site model, which used three additional parameters, showed significant improvements over the single-site model. The two-site model was validated using the data from two extra experimental runs, which were not employed in the parameter estimation process. Most of the model predictions fall within the 95% confidence intervals of the experimental data.