Abstract: A method for preparing C.sub.4 to C.sub.10 .alpha.-olefins employing trialkyl aluminum compounds, in a growth zone having a recirculation rate through an external heat transfer zone such that the contents of the zone are recirculated in a period of time sufficient to remove the heat of the reaction using added lower .alpha.-olefins at 100.degree.-150.degree. C., 200-2000 psig, and 5-90 minute contact time followed by displacement with lower .alpha.-olefins in a static mixer zone to free the growth .alpha.-olefins and regenerate the trialkyl aluminum compounds. The growth .alpha.-olefins are separated with all of the lower .alpha.-olefins recycled to the growth and displacement steps.