N-doped Metallocene Catalysts for Synthesis of High Quality Lubricant Base Oils from Fishcher–Tropsch Synthesized α-Olefin

Derivatives of 2,4-dimethyldihydrocyclopentadiene were prepared, characterized by NMR spectroscopy, which was applied to 1-decene oligomerization. A two-step activation method in which both triisobutylaluminium (TIBA) and methyl aluminoxane (MAO) were co-used in sequence particularly been developed for N-doped ligand catalyst. N-doped catalyst had a very high polymerization conversion at 60–110 °C by varying the reaction temperature at 20 eq. of TIBA and 100 eq. of MAO, reaching 89.95% at 80 °C. In addition, oligomers with different viscosity grades could be obtained by adjusting the temperature. At optimized reaction conditions 75 °C, 10 eq. of TIBA and 50 eq. of MAO activation, the single pass conversion of 91.33% was achieved. The obtained oligomers had a high viscosity index above 170 at KV 100  = 6. In addition, the two-step activation method was used to compare with the conventional one-step activation method on catalysts with three different ligands of zirconium chloride. A high catalytic productivity was achieved by the two-step activation process. Depending on the nature of the ligands used, β-hydride elimination, 2,1 insertion and 1,2 rearrangement were detected as main chain release mechanisms. Meanwhile, the pathways of oligomer formation were also summarized. In brief, N-doped complex is promising catalysts for the production of high quality lubricant base oils due to their high catalytic activity and high thermal stability. Graphical Abstract