Premium
Hydrogen Effects for Propylene Polymerization with Ultra Low TiCl 3 Loading MgCl 2 ‐Supported Catalyst
Author(s) -
Kouzai Iku,
Wada Tooru,
Taniike Toshiaki,
Terano Minoru
Publication year - 2008
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200751426
Subject(s) - polymerization , catalysis , hydrogen , dissociation (chemistry) , stereospecificity , steric effects , inert , chemistry , materials science , polymer chemistry , photochemistry , inorganic chemistry , organic chemistry , polymer
Abstract Hydrogen effects for propylene polymerization were investigated with ultra low TiCl 3 loading MgCl 2 ‐supported catalysts in which the electric states of Ti species can be almost uniform. Hydrogen did not affect the catalyst activity, while the efficiency of hydrogen as a chain transfer agent was found to depend on the Ti content of the catalyst and the stereospecificity of the polymerization sites: Hydrogen was effective for isospecific sites independent of Ti contents, but inert for aspecific sites only at the extremely low Ti content. These results were explained within the island model, where isospecific sites may be located in the islands with other Ti species in their surroundings acting, as a steric hindrance for isospecific polymerization and as hydrogen dissociation sites after deactivation. Most of the aspecific sites should be isolated only at the extremely low Ti content. These isolated sites have no other Ti species in their surroundings, i.e. no hydrogen dissociation sites, and are inert to hydrogen.