{HEAD ~ The H2} is separated and recycled to the alcohol synthesis zone as a second source of {TAIL ~ H2} 
{ HEAD ~ The H2 } is separated and recycled to the alcohol synthesis zone as a second source of { TAIL ~ H2 }
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL