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Rapid evaluation of catalysts and MAO activators by kinetics: what controls polymer molecular weight and activity in metallocene/MAO catalysts?
Ist Teil von
Dalton transactions : an international journal of inorganic chemistry, 2013-07, Vol.42 (25), p.94-948
Ort / Verlag
England
Erscheinungsjahr
2013
Link zum Volltext
Quelle
MEDLINE
Beschreibungen/Notizen
The influence of methylaluminoxane (MAO) catalyst activators of different concentrations and preparative histories on the performance of 1-hexene polymerisations was investigated by kinetic methods, using
rac
-Me
2
Si(2-Me-Benz[
e
]Ind)
2
ZrCl
2
as the standard catalyst precursor. Fast sampling and analysis allow the time dependence of monomer conversion and the growth of the number-average polymer molecular weight to be determined at a sufficiently short timescale to make this a feasible method for routine catalyst evaluation. Differences in productivity, polymer molecular weight and active species count are shown to be primarily a linear function of the trimethylaluminium concentration. The results in toluene and heptane as solvents are compared; the data show that the inferior performance in heptane is due to a substantially lower active species concentration.
Kinetic methods allow rapid and highly sensitive catalyst evaluation. Catalyst productivity, polymer molecular weight and active species count are controlled simply by adjusting the trimethylaluminium concentration.