Premium
Ethylene polymerization with methylaluminoxane/(nBuCp) 2 ZrCl 2 catalyst supported on silica and silica‐alumina at different Al MAO /Zr molar ratios
Author(s) -
Carrero A.,
van Grieken R.,
Paredes B.
Publication year - 2010
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.33189
Subject(s) - methylaluminoxane , metallocene , crystallinity , polymerization , materials science , catalysis , dispersity , polymer chemistry , post metallocene catalyst , ethylene , molar mass , thermogravimetry , nuclear chemistry , chemistry , inorganic chemistry , organic chemistry , composite material , polymer
Methylaluminoxane (MAO)/(nBuCp) 2 ZrCl 2 metallocene catalytic system was supported on silica and silica‐alumina. The Zr loading was varied between 0.2–0.4 wt %, and the MAO amount was calculated to get (Al MAO /Zr) molar ratios between 100 and 200, suitable for the industrial ethylene polymerization of supported metallocene catalysts. Catalytic activity was statistically analyzed through the response surface method. Within the ranges studied, it was found that Zr loading had a negative effect on polymerization activity, which increases with the (Al MAO /Zr) molar ratio. Catalysts supported on silica‐alumina are more active than those supported on silica, needing less MAO to reach similar productivity, which constitutes an important advantage from an economical and environmental point of view. Supported catalysts were characterized by ICP‐AES, SEM‐energy‐dispersive X‐ray spectrometer, and UV‐Vis spectroscopy, whereas polyethylenes were characterized by GPC and DSC. Molecular weight and crystallinity are not influenced by Zr loading or (Al MAO /Zr) ratio, in the range studied. In general, silica‐supported MAO/( n BuCp) 2 ZrCl 2 catalysts give polyethylenes with higher molecular weight and polydispersity but lower crystallinity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011