Heterocene Catalysts and Reaction Temperature Gradient in Dec-1-ene Oligomerization for the Production of Low Viscosity PAO Base Stocks

Hydrogenated oligomers of higher α-olefins (primarily,
dec-1-ene)
with uniform structure represent high-quality poly-α-olefin
oil (PAO) base stocks. High yields of lightweight dec-1-ene oligomers
(DPn = 3–4) can be achieved by
using 5,10-dihydroindeno[1,2-b]indole-based zirconium ansa-complexes, “heterocenes”. Unusual catalytic
behavior of heterocenes served as a starting point for the present
study, during which new, more synthetically available and active heterocene
precatalysts were synthesized, and a novel oligomerization method,
based on a reaction temperature gradient, was developed. A gradual
decrease of the oligomerization temperature as dec-1-ene was consumed
resulted in decreased dimer formation (down to 10%) and increased
oligomer yields (up to 84%). After hydrogenation, low- and medium-viscosity
PAO base oils with uniform structure and high viscosity indexes were
obtained.