a simplified process for preparing polyolefins from saturated hydrocarbons is provided . the process involves partial and selective dehydrogenation of a saturated hydrocarbon in the presence of oxygen to form an olefin , unreacted hydrocarbon , and water , and optionally other by - products and oxygen . the water , other by - products , and oxygen are separated from the olefin and unreacted hydrocarbon . no other separation is performed . the olefin and unreacted hydrocarbon are polymerized in the presence a polymerization catalyst or initiator to make polyolefin . solid polyolefin is separated from unreacted hydrocarbon , which is recycled to the dehydrogenation reaction .