One type of commercial lubricant is a polyalphaolefin (PAO) lubricant. PAOs can be prepared via the oligomerization of alpha-olefins (typically 1-decene, sometimes 1-octene and 1-dodecene). Other chemistry that is relevant includes ExxonMobil's Ultra High Viscosity Index PAO lubricants. Currently, PAOs are synthesized by a two-step reaction sequence from linear alpha-olefins, which are derived from ethylene. The first step is the synthesis of a mixture of oligomers, which are polymers of relatively low molecular weight. This first step is catalyzed using a boron trifluoride catalyst in conjunction with a protic catalyst such as water, alcohol, or a weak carboxylic acid. However, it has been observed that boron trifluoride catalysis causes excess skeletal branching during the oligomerization process. An increase in the amount of skeletal branching directly correlates with an increase in the number of tertiary hydrogens in the molecule, which are prone to oxidation, and therefore exhibit poor stability when used in lubricants. The second step in the manufacturing process entails hydrogenation of the unsaturated oligomer.
However, in order to generate PAOs, a four-stage process is required: 1) ethylene oligomerization, 2) separation of the alpha-olefin (e.g. 1-decene), 3) oligomerization of the alpha-olefin, and 4) hydrogenation). Therefore, there is a need for a process to generate a branched hydrocarbon-based lubricant at a lower cost of manufacture compared to existing PAO products made from oligomerization of alpha-olefins. In addition, there is a need for a branched hydrocarbon-based lubricant that imparts improved performance relative to PAO lubricants, such as higher viscosity index.
USPTO Backgrounds
USPTO Backgrounds