Selective catalytic trimerization of alkenes

The selective trimerization of ethylene constitutes a useful source of 1-hexene, an important co-monomer for the prodn. of linear low-d. polyethylene (LLDPE), while selective trimerization of α-olefins could lead to new methodol. for upgrading light hydrocarbons to more valuable fuels and lubricants. I will discuss several aspects of Cr- and Ti-catalyzed trimerization studied by our group, including: 1) a diagnostic test for the metallacyclebased mechanism proposed to account for selectivity; 2) spectroscopic evidence that a very small fraction of total species is responsible for activity with a Cr-based catalyst; 3) a stoichiometrically activated, homogeneous Ti-based catalyst that both permits detailed mechanistic study for ethylene trimerization and is active for α- olefin trimerization; 4) a supported version of the Ti catalyst that gives significantly improved performance; and 5) a co-supported tandem catalyst for LLDPE prodn. using ethylene as the sole feed.