Abstract: Method for operating a two-stage hydroprocessing system includes introducing a feedstock and a first-stage gas to a first reaction zone a first pressure to generate a first-stage product stream; introducing the first-stage product stream to a first separation unit to separate an intermediate feedstock from a spent gas; introducing the intermediate feedstock and a second-stage gas to a second reaction zone a second pressure which is greater than the first pressure to generate a second-stage product stream; introducing the second-stage product stream to a second separation unit to separate a hydroprocessed product and an intermediate gas; feeding the intermediate gas directly to the first reaction zone as the first-stage gas; feeding spent gas to an amine unit and then compressor to generate recycled gas; and feeding recycled gas to the second reaction zone as the second-stage gas.