{TAIL ~ The catalyst}, water and unreacted methanol can be recovered and recycled back to {HEAD ~ the reaction zones} 
{ TAIL ~ The catalyst } , water and unreacted methanol can be recovered and recycled back to { HEAD ~ the reaction zones }
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD