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Ethylene polymerization over supported MAO/( nBuCp) 2ZrCl 2 catalysts: Influence of support properties
Ist Teil von
European polymer journal, 2007, Vol.43 (4), p.1267-1277
Ort / Verlag
Elsevier Ltd
Erscheinungsjahr
2007
Link zum Volltext
Quelle
Elsevier ScienceDirect Journals Complete
Beschreibungen/Notizen
The catalytic system methylaluminoxane (MAO) and bis(
n-butylcyclopentadienyl)zirconium dichloride ((
nBuCp)
2ZrCl
2) was immobilized on commercial silica, silica–alumina and aluminophosphate calcined at different temperatures. The properties of the supports were determined by using N
2 adsorption–desorption isotherms at 77
K, FT-IR spectroscopy and SEM. After aluminium and zirconium impregnation, the catalysts were analyzed by ICP-AES, FT-IR and UV–vis spectroscopy. Ethylene polymerizations were carried out in a Schlenk tube at 70
°C and 1.2
bar of ethylene pressure. The polyethylene obtained was characterized by GPC, DSC and SEM.
Catalysts supported on silica–alumina exhibited higher polymerization activity than those supported on silica and aluminophosphate. Besides, the activity of MAO/(
nBuCp)
2ZrCl
2 catalytic system supported on silica–alumina and aluminophosphate decreased strongly with support calcination temperature, while remained almost constant when silica was employed as support. All these experimental features suggest a role of the support acid properties and hydroxyl group population in the generation of active polymerization species.