Abstract: A process for producing a polyolefin comprising a combination of liquid phase polymerization of ?-olefin conducted in one or more liquid phase polymerization reactors and gas phase polymerization of ?-olefin conducted in one or more gas phase polymerization reactors after the liquid phase polymerization in a material flow.

Abstract: A process for producing a polyolefin comprising a combination of liquid phase polymerization of ?-olefin conducted in one or more liquid phase polymerization reactors and gas phase polymerization of ?-olefin conducted in one or more gas phase polymerization reactors after the liquid phase polymerization in a material flow, the process comprising: step A of polymerizing liquid ?-olefin in the presence of a catalyst in a first reactor for liquid phase polymerization to produce a slurry comprising unreacted liquid ?-olefin and a polymer powder containing the catalyst, step B of causing gas comprising ?-olefin to flow in a second reactor for gas phase polymerization while keeping the second reactor unfilled with a seed powder, step C of transferring the slurry produced in the first reactor into the second reactor unfilled with a seed powder in which the gas comprising ?-olefin is caused to flow, step D of vaporizing the liquid ?-olefin included in the slurry transferred from the first reactor, polymerizing the va