{HEAD ~ A co processing} combining {TAIL ~ a first selective catalytic bed} consisting of only one metal element selected from group VIB metals and of at least one conventional hydrotreating bimetallic catalytic bed 
{ HEAD ~ A co processing } combining { TAIL ~ a first selective catalytic bed } consisting of only one metal element selected from group VIB metals and of at least one conventional hydrotreating bimetallic catalytic bed
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH