Abstract: A hydroconversion effluent separation process is provided.The effluent from the hydroconversion zone is passed to a hot high pressure separation zone. The gas phase from that zone is then passed to a cold high pressure separation zone while the liquid hydrocarbon bottoms is passed to a hot low pressure separation zone. The gas phase is partially condensed in the cold high pressure separation zone to obtain a hydrogen-rich gas and a liquid hydrocarbon bottoms. A portion of the hydrogen-rich gas is recycled to the hydroconversion zone. A second portion is sent to a hydrogen purification step, most preferably by membrane separation, and the purified gas is recycled to the hydroconversion zone. The overhead from the hot low pressure separation is fed to a cold low pressure separation zone. The gas phase from the cold low pressure separation zone is recycled to the hydroconversion zone. Preferably, two cold low pressure separation zones are utilized in the process.

Abstract: Middle distillate oil is produced with a minimum production of lighter hydrocarbons by (1) contacting hydrogen gas and a heavy distillate oil containing nitrogenous hydrocarbons with a catalyst in a first reaction zone under selected conditions, and (2) contacting hydrogen gas and at least a portion of the resulting effluent from the first zone with a catalyst in a second reaction zone under selected conditions. In each zone the catalyst is a composite of an amorphous silica-alumina carrier and a hydrogenation component wherein the silica and hydrogenation component are highly dispersed.