{TAIL ~ Propylene}, oxygen, and hydrogen are preferably fed to the reactor at or near {HEAD ~ the bottom} of the reactor 
{ TAIL ~ Propylene } , oxygen , and hydrogen are preferably fed to the reactor at or near { HEAD ~ the bottom } of the reactor
TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH