Premium
Supported ( n BuCp) 2 ZrCl 2 Catalysts: Effects of Selected Lewis Acid Organotin Silica Surface Modifiers on Ethylene Polymerization
Author(s) -
Akhtar Muhammad N.,
Atiqullah Muhammad,
Moman Akhlaq A.,
AbuRaqabah Atieh H.,
Ahmed Neaz
Publication year - 2008
Publication title -
macromolecular reaction engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 32
eISSN - 1862-8338
pISSN - 1862-832X
DOI - 10.1002/mren.200800006
Subject(s) - lewis acids and bases , catalysis , polymer chemistry , ethylene , polymerization , chemistry , metallocene , organic chemistry , polymer
This study investigated the effects of several organotin silica surface modifiers on the ethylene polymerization performance of ( n BuCp) 2 ZrCl 2 ‐based supported catalysts in which MAO and metallocene were sequentially loaded. Each organotin compound acted as a spacer, increasing the catalyst activity. However, the catalyst activity and $\overline M _{\rm w}$ of the resulting polyethylenes varied as follows: Activity and fractional Sn + charge: n BuSn(OH) 2 Cl > MeSnCl 3 > n BuSnCl 3 > Reference catalyst; and, $\overline M _{\rm w}$ : Reference catalyst > n BuSnCl 3 > MeSnCl 3 > n BuSn(OH) 2 Cl. The above catalyst activity rating was explained considering the influence of the Lewis acidity, that is, the fractional Sn + charge of the organotin modifiers on the generation, concentration, and electron density at the active [( n BuCp) 2 ZrMe] + cation. All the catalysts showed fairly stable kinetic profiles and produced narrow molecular weight distribution resins; 2.8 ≤ PDI ≤ 3.