US Patent 8410329 Ethylene separation

A polyethylene production process, comprising contacting ethylene and a polymerization catalyst under suitable reaction conditions to yield a polymerization product stream, separating a light gas stream from the polymerization product stream, wherein the light gas stream comprises ethane and unreacted ethylene, contacting the light gas stream with an absorption solvent system, wherein at least a portion of the ethylene from the light gas stream is absorbed by the absorption solvent system, removing unabsorbed gases of the light gas stream from contact with the absorption solvent system to form a waste gas stream, and recovering ethylene from the absorption solvent system.