Synthesis of Novel Dendritic Bridging Nickel Complex for Oligomerization of Olefins

Abstract

A novel N,N-bidentate dendritic bridging pyridine-imine ligand and its nickel complex were prepared and characterized by elemental analysis, Fourier transform infrared spectrometry (FTIR) and electrospray ionization-mass spectrometry(ESI-MS). The dendritic nickel complex was used as a precatalyst in the oligomerization of ethylene with the co-catalyst ethyl dichloroaluminum(EtAlCl2), as well as a precursor in the oligomerization of 1-pentene. The effects of the reaction time, reaction pressure and the molar ratio of Al/Ni on the catalytic activities and the distribution of the product in the oligomerization were investigated. The dendritic nickel complex revealed the selectivity of higher olefins(C-10-C-14) reached up to 93% and the catalytic activity was 0.99x10(6) g/(mol Ni.h) at the reaction time of 60 min, ethylene pressure of 0.5 MPa and the molar ratio of Al/Ni of 150 in the oligometization of ethylene. At the reaction time of 60 min and the molar ratio of Al/Ni of 300, the catalyst also had excellent catalytic performance in the oligomerization of 1-pentene. The selectivity of C-20 reached to 70.5% and the catalytic activity was 2.47x10(5) g/(mol Ni.h). The dendritic nickel complex exhibited good catalytic activities and selectivities for higher carbon number olefins in ethylene oligomerization and 1-pentene oligomerization.