Process for recovery of ethylene oligomers

In the process for the oligomerization of ethylene to linear alpha-olefins wherein ethylene is oligomerized by contact in liquid phase at elevated pressure with a solution of an oligomerization catalyst composition comprising catalytically active nickel complex in an aliphatic diol solvent to afford a reaction product made up of (1) a liquid solvent phase containing dissolved catalyst, (2) a liquid hydrocarbon phase comprising ethylene oligomers containing dissolved ethylene, catalyst, diol solvent and a minor amount of diol solvent decomposition products and (3) a gaseous ethylene phase, said ethylene oligomers being recovered by separating the liquid hydrocarbon phase from the gaseous ethylene and at least part of the liquid solvent phase under pressure after which the separated liquid hydrocarbon phase is sequentially washed with sufficient aliphatic diol solvent to remove any residual amount of active catalyst, subject to reduced pressure to flash off dissolved ethylene and scrubbed with water to remove residual solvent;

• the improvement which comprises, contacting the liquid hydrocarbon phase, immediately after water scrubbing, with sufficient aqueous acid at elevated temperature to hydrolyze and extract the diol solvent decomposition products, said aqueous acid having a pH below about 5, and recovering therefrom a liquid hydrocarbon phase substantially free of diol solvent decomposition products.