Abstract
Silylated-salicylaldimine nickel(II) (1) was synthesized with 3-aminopropyl-trimethoxysilane, salicylaldimine and NiCl2·6H2O, and carbon nanotube-supported salicylaldimine-nickel catalyst (2) was synthesized by anchoring 1 covalently to multi-walled carbon nanotubes. The chemical structure of the synthesized ligand was characterized by elemental analysis, 1H NMR and FT-IR. Compounds were characterized by XRD, FT-IR, TGA and XPS and were used as precatalysts for ethylene oligomerization. The catalytic activity and the selectivity of C6 olefin for 2 were much higher than those for 1 in ethylene oligomerization. Compared with other cocatalysts, the catalytic activity and selectivity to C6 olefin for 2 were the highest using MAO as cocatalyst. When Al/Ni molar ratio was 700, at 25 °C, 30 min and pressure was 0.5 MPa, the catalytic activity of 5.85 × 106 g·(mol Ni·h)−1 and selectivity of 94.7% toward C6 olefin for 2 in cyclohexane were observed. Compared with 1, catalyst 2 had the good repeatability and thermal stability, with catalytic activity of 4.29 × 106 g·(mol Ni·h)−1 and the selectivity of C6 olefin was 84.3% after the third oligomerization reaction.
Acknowledgment
The authors are grateful to State Key Lab of Inorganic Synthesis and Preparative Chemistry of Jilin University for the characterization work.
Disclosure statement
No conflict of interest exits in the manuscript, and manuscript is approved by all authors for publication.