Abstract

LARA, Alí Gabriel; PAPA, José; ALBANO, Carmen  and  KARAM, Arquímedes. Kinetic modeling of ethylene polymerization over chromium non-metallocene catalysts. Rev. Fac. Ing. UCV [online]. 2011, vol.26, n.3, pp.135-145. ISSN 0798-4065.

This work was focused on the kinetic modeling of ethylene polymerization over homogeneous chromium non-metallocene catalyst in order to correlate the experimental data obtained. Pursuing this objective, a mathematical model which evaluates two reaction mechanisms was proposed: the first, coordination/insertion and the second, coordination/insertion/transfer of ethylene. To solve the system of equations, a routine in Matlab^® was developed which is a set of two modules. The first module is the starting seeds for all unknown kinetic parameters, and the second one is a regression algorithm whose purpose is minimize the sum of the squares of the differences between the calculated reaction rate and experimental data. The predicted rates were compared with experimental data available, using statistical techniques, with regression coefficient R² = 0,989. From the analysis of the effect of ethylene concentration over reaction rates, it was observed that when the temperature is less than 302 K, the polymerization is a first-degree reaction at low concentrations of ethylene, while at high concentrations becomes a zero-degree reaction. By contrast, when the reaction temperature is equal or greater than 302 K, it is a first-degree reaction over the entire range of ethylene concentrations.

Keywords : Modeling; Kinetics; Polymerization; Ethylene; Non-Metallocene.