1. QUATTOR, Rua Hidrogênio, 1404, Pólo Petroquímico, CEP: 42810‐010, Cama?ari, BA, Brazil;2. LCPP–CNRS/ESCPE‐Lyon, 43 Blvd du 11 Novembre 1918, Bat 308F, BP 2077, 69616 Villeurbanne Cedex, France;3. Programa de Engenharia Química/COPPE, Universidade Federal do Rio de Janeiro, Cidade Universitária, CP 68502, Rio de Janeiro, 21945‐970, RJ, Brazil;4. Department of Chemical Engineering, Queen's University, 19 Division Street, Kingston, ON, K7L 3N6, Canada
Abstract:
The very early stages of gas‐phase ethylene polymerization on an SiO2‐supported Ziegler–Natta catalyst were studied with the help of a short‐stop reactor. The short‐stop‐reactor‐based technique was useful in studying nascent polymerization, providing insights at very short, controlled times into important phenomena regarding catalyst fragmentation and the activation and deactivation of catalyst sites that take place during the very early stages of the reaction. Experimental results indicate that the growth of the polymer chains occurs at unsteady conditions during the initial stages of the polymerization. Hydrogen has a strong influence on the initial kinetics, leading to a significant decrease of polymerization activity. Polymer crystallinity increases with the reaction time, probably due to the formation of long chains with a high degree of crystallinity.
