Patent ID: 7880047

Claim:
A continuous or semi-continuous process for forming a liquid polyalphaolefin having a kinematic viscosity at 100° C. of less than 1000 cSt, comprising: (a) adding a C8-C12 α-olefin, a C8-C12 saturated hydrocarbon, hydrogen, and a catalytically effective amount of a catalyst system to a reaction vessel (b) polymerizing the C8-C12 α-olefin in the reaction vessel in the presence of the C8-C12 saturated hydrocarbon, the hydrogen, and the catalyst system to form an initial crude liquid polyalphaolefin product comprising the polyalphaolefin, unreacted monomer, and C8-C12 saturated hydrocarbons, during which polymerization monomer is continuously or semi-continuously fed to the reaction vessel and crude liquid polyalphaolefin product is continuously or semi-continuously removed from the reaction vessel, (c) separating from the removed crude liquid polyalphaolefin product an enriched saturated hydrocarbon stream comprising C8-C12 saturated hydrocarbons and unreacted monomer, and (d) removing 5 to 35 weight percent of the enriched saturated hydrocarbon stream from the polymerization system as a purge stream to prevent the buildup of byproducts and contaminants and adding back to the reaction vessel 65 to 95 weight percent of the enriched saturated hydrocarbon stream, wherein the C8-C12 saturated hydrocarbons are maintained in the reaction vessel at a level of from 8 to 40 weight percent, based on the combined weight of the C8-C12 α-olefin, the C8-C12 saturated hydrocarbon and the polyalphaolefin contained in the reaction vessel.