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Influence of support friability and concentration of α‐olefins on gas‐phase ethylene polymerization over polymer‐supported metallocene/methylaluminoxane catalysts
Author(s) -
Hammawa Hassan,
Wanke Sieghard E.
Publication year - 2007
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.25527
Subject(s) - comonomer , methylaluminoxane , metallocene , friability , catalysis , polyethylene , 1 hexene , ethylene , materials science , polymer chemistry , tacticity , linear low density polyethylene , post metallocene catalyst , polymerization , polymer , nuclear chemistry , organic chemistry , chemistry , composite material , ethyl cellulose
The effects of support friability (Φ) and ethylene/comonomer ratios were investigated over supported metallocene/methylaluminoxane catalysts prepared with nine different porous polymeric supports and various comonomer concentrations with a 2‐L reactor operated in the semibatch gas‐phase mode at 80°C and 1.4 MPa. Φ of the supports was measured with a newly devised method. The performance of the supported catalysts depended on support Φ as follows. The average homopolymerization activities varied from less than 6 t of polyethylene (PE) (mol of Zr) −1 h −1 for low‐Φ catalysts to 10–20 t of PE (mol of Zr) −1 h −1 for moderate‐Φ catalysts and up to 100 t of PE (mol of Zr) −1 h −1 for the high‐Φ catalysts. The presence of 1‐hexene and propylene comonomers increased the activity of the low‐Φ catalysts by up to 20‐fold and 50‐fold, respectively; that is, there were very marked comonomer effects. Activity enhancement by 1‐hexene was less than 3‐fold for the moderate‐Φ catalysts, whereas the high‐Φ catalysts showed little activity enhancement. Sometimes, 1‐hexene even resulted in activity reductions. Very different particle morphologies were obtained with the catalysts of different Φ's. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 514–527, 2007