NOVELTY - Purging propane in a polypropylene manufacturing process, comprises polymerizing propylene in a polymerization zone, withdrawing an effluent and sending to a separation zone to produce polypropylene, optionally the solvent and a stream, optionally recycling the solvent to the polymerization zone, sending the propylene and propane stream to a splitter to produce an overhead consisting of propylene recycled to the polymerization zone and a rich propane bottom stream, sending the bottom stream to a membrane separation zone to produce a permeate and a purge, and recycling the permeate.    USE - The method is useful for purging propane in a polypropylene manufacturing process (claimed).    ADVANTAGE - The method produces the permeate having an enhanced propylene content and a reduced propane content and the purge having an enhanced propane content and a reduced propylene content.    DETAILED DESCRIPTION - Purging propane in a polypropylene manufacturing process comprises (a) polymerizing propylene in a polymerization zone, (b) withdrawing an effluent comprising polypropylene, propylene, propane and optionally a solvent from the polymerization zone, (c) sending the effluent to a separation zone to produce polypropylene, optionally the solvent and a stream comprising propylene and propane, (d) optionally recycling the solvent to the polymerization zone, (e) sending the propylene and propane stream to a splitter to produce an overhead consisting essentially of propylene recycled to the polymerization zone and a rich propane bottom stream comprising a minor part of propylene, (f) sending the bottom stream to a membrane separation zone to produce a permeate having an enhanced propylene content and a reduced propane content and a purge having an enhanced propane content and a reduced propylene content, and (g) recycling the permeate to the polymerization zone. An INDEPENDENT CLAIM is included for debottlenecking of a polypropylene manufacturing facility comprising the polymerization zone, the separation zone to recover the polypropylene, optionally the solvent and the stream comprising propylene and propane, the membrane separation zone and the splitter to separate propane and propylene, where, the membrane separation zone is provided and fed with the splitter bottom to produce the purge and the permeate recycled to the polymerization zone.