Hydrogen response in liquid propylene polymerization: Towards a generalized model

Liquid propylene batch experiments in the absence of a gas phase have been carried out using a highly-active MgCl2/TiCl4/phthalate/silane/AlR3 catalyst at varying temperatures (60-80°C) and molar hydrogen-monomer ratios of 0-10 mmol/mol. With increasing hydrogen concentration the: 1. polymerization rate increases rapidly, reaching a constant value at concentrations above 1.4 mmol/mol; 2. pseudo-first-order catalyst deactivation constant increases; 3. molecular weight decreases; 4. polydispersity decreases slightly; but average molecular weight and polydispersity increase with increasing temperature. Polymerization rate, deactivation constant, and average molecular weight can be modeled based on a consistent dormant site mechanism assuming an (averaged) quasi-single-site model.