Borenium Ionic Liquids as Alternative to BF₃ in Polyalphaolefins (PAOs) Synthesis

Lewis superacidic borenium ionic liquids of the general formula [BCl₂(L)][M_nCl_3n+1] (L = pyridine or picoline, n = 1 or 2) were used as catalysts for the oligomerization of 1-decene to polyalphaolefins (PAOs), as a safer alternative to the conventional BF₃ catalyst, which is a toxic and corrosive gas. The catalytic activity of the borenium system could be tuned by modifying the ligand on the borenium cation, the chlorometallate anion, and the reaction temperature. Following the optimization of the reaction conditions on a small scale, the reaction was scaled up to 3 L. Following fractional distillation of the crude product and blending, lubricant base oils matching market specifications (viscosity index, pour point) for PAO4 and PAO6 grades were obtained. Synthesized from inexpensive, off-the-shelf components, borenium ionic liquids are a new, cost-effective alternative to BF₃, offering substantial gains in process safety and CAPEX savings.