Improved heterogenized catalysts for selective propylene oligomerization to 2,3-dimehtylbutenes prepared by oxidative addition of polymer-anchored #beta#-dithioacetylacetonate ligands to nickel(0) complexes

摘要

A novel approach for obtaining heterogenized catalysts, via oxidative addition of polymer-bound 13-dithioacetylacetonate (sac sac) ligands to nickel(O) complexes was reported and their performances were invcstigated in the propylene oligomeriza- tion, in terms of activity and selectivity to 2,3-dimethylbutenes (D MB). In particular, the effect of the nature of the ancillary phosphine ligand as well as of the organoaluminium co-catalyst was studied. The influence of the addition to the reaction medium of chlorinated promoters was also checked. The results indicated that the catalysts prepared by this route were more active and selective towards D MB as compared with those pr~viously prepared by an exchange reaction method. When basic alkyl phosphines, such as tricyclohexylphosphine (PCY3) and triisopropylphosphine (piPr3), and organoaluminium co-catalysts with suitable Lewis acidity, such as Et2AIC1, were used, the resulting catalysts displayed a very high selectivity to D MB ( ~80% ) and an extremely high productivity (turnover frequency equal to 74,000 h-1 ), the latter being much higher as compared with that previously obtained with the homogeneous counterparts.