Processes to produce poly alpha-olefin trimer and apparatus therefor

A process to produce a poly alpha-olefin (PAO), comprising:

• a) introducing a first alpha-olefin to a first catalyst system comprising activator and a metallocene compound into a continuous stirred tank reactor or a continuous tubular reactor under first reactor conditions, wherein the first alpha-olefin is introduced to the reactor at a flow rate of about 100 g/hr or more, to form a first reactor effluent comprising at least 60 wt % of PAO dimer and 40 wt % or less of higher oligomers, where the higher oligomers are oligomers that have a degree of polymerization of 3 or more;
• and
• b) introducing the first reactor effluent and a second alpha-olefin to a second catalyst composition comprising an acid catalyst in a second reactor to form a second reactor effluent comprising PAO trimer,
• wherein the higher oligomers in the first reactor effluent are not separated from the first effluent stream prior to introduction into the second reactor.