Metallocene-catalyzed oligomerizations of 1-butene and α-olefins: Toward synthetic lubricants

Abstract

In this study we found that the oligomerizations of 1-butene with various higher α-olefins (1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene) in the presence of the catalyst (Me4Cp)2ZrCl2 and the co-catalyst methylaluminoxane yielded low-molecular-weight oily oligomers. 1H and 13C NMR spectroscopy revealed that the major olefinic bonds of these oligomers were terminal vinylidene and internal trisubstituted vinylidene units. The chain termination of oligomerization of 1-butene alone favored chain transfer to the co-catalyst, which process was favored after adding α-olefin and affected only slightly by the lateral size of the α-olefin. The addition of the α-olefin to 1-butene decreased the oligomerization activity, oligomer molecular weight and kinematic viscosity, but increased oligomer viscosity index. Moreover, the oligomerization activity, oligomer molecular weight and kinematic viscosity were presented as a function of the concentration of α-olefin, the oligomerization temperature and the Al/Zr ratio.