A hydrotreating process in downward cocurrent reactors with a set against the current

A hydrotreating process in fixed bed against the current simulated comprising two hydrotreating zones to co-run down and two separation zones in which the second hydrotreating zone is disposed below the first separation zone so as to create a hydrostatic head of liquid in a liquid Ha leg connecting the first separation zone to the second hydrotreating zone, the height Ha generating a pressure difference for achieving the flow of the first liquid fraction to the second zone gravity way hydrotreating without the need for a pump.