Patent ID: 7067597

Claim:
A process for making polypropylene, comprising the steps of: a) separating a propylene stream and a dimethyl ether stream from an olefin stream, with the propylene stream being separated as an overhead distillation stream and the dimethyl ether stream being separated as a bottoms distillation stream; b) recovering an intermediate grade propylene stream from the overhead stream, wherein the intermediate grade propylene stream contains less than 99.5 wt % and at least 95 wt % propylene; c) contacting the intermediate grade propylene stream with polypropylene forming catalyst to form polypropylene and unreacted by-product; d) recovering propylene from the unreacted by-product to form a recycle stream; and e) contacting the recycle stream with the polypropylene forming catalyst to form additional polypropylene product.