{HEAD ~ A process} for demetalation, desulfurization and dewaxing of residual oil has been discovered using {TAIL ~ a two stage process} 
{ HEAD ~ A process } for demetalation , desulfurization and dewaxing of residual oil has been discovered using { TAIL ~ a two stage process }
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL