Two phase hydroprocessing process as pretreatment for tree-phase hydroprocessing process

A process for hydroprocessing a hydrocarbon feed which comprises:

• (a) providing a first two-phase hydroprocessing zone in sequence and in liquid communication with a three-phase hydroprocessing zone, wherein the two-phase hydroprocessing zone comprises a liquid recycle and at least two catalyst beds disposed in sequence and in liquid communication, wherein each catalyst bed is disposed in a liquid-full reactor and contains a catalyst having a volume, the catalyst volume increasing in each succeeding bed;
• the three-phase hydroprocessing zone comprises a single-liquid pass catalyst bed disposed in a trickle bed reactor, wherein the single-liquid-pass catalyst bed is outside any liquid recycle stream;
• (b) contacting a hydrocarbon feed with (i) a diluent and (ii) hydrogen to produce a hydrocarbon feed/diluent/hydrogen mixture, wherein hydrogen is dissolved in the mixture to provide a liquid feed;
• (c) contacting the liquid feed with a first catalyst in a first catalyst bed of the first two-phase hydroprocessing zone to produce a product effluent;
• (d) contacting the product effluent from a preceding catalyst bed with a current catalyst in a current catalyst bed of the first two-phase hydroprocessing zone, wherein the preceding catalyst bed is immediately upstream of and in liquid communication with the current catalyst bed to produce a current product effluent, such that when the preceding catalyst bed is the first catalyst bed, the product effluent from the preceding catalyst bed is the product effluent from the first catalyst bed, produced in step (c);
• (e) recycling a portion of the current product effluent from a final catalyst bed of the first two-phase hydroprocessing zone as the liquid recycle for use in the diluent in step (b) at a recycle ratio of from about 0.1 to about 10, wherein the final catalyst bed contains a final catalyst and is a current catalyst bed having no succeeding catalyst bed in the first two-phase hydroprocessing zone;
• (f) contacting hydrogen and the remaining portion of the current product effluent from the final catalyst bed of the first two-phase hydroprocessing zone with one or more catalysts in one or more single-liquid-pass catalyst beds, wherein each single-liquid-pass catalyst bed in this step (f) is disposed in (i) a liquid-full reactor in a second two-phase hydroprocessing zone, or (ii) a trickle bed reactor in the three-phase hydroprocessing zone to produce a product effluent,
• provided that when the remaining portion of the current product effluent is contacted with a catalyst in a single-liquid-pass catalyst bed disposed in a liquid-full reactor, there is a further step comprising:
• (f′) contacting the product effluent from the single-liquid-pass catalyst bed disposed in a liquid-full reactor and a hydrogen-containing gas with a catalyst in a single-liquid-pass catalyst bed disposed in a trickle bed reactor in the three-phase hydroprocessing zone;
• and further provided that when the single-liquid-pass catalyst bed is disposed in a trickle bed reactor, the hydrogen is provided as a hydrogen-containing gas wherein at least a portion of the hydrogen-containing gas is a hydrogen-rich recycle gas stream and wherein the hydrogen-containing gas is added in an amount sufficient to maintain a continuous gas phase in the trickle bed reactor and the product effluent is a trickle bed product effluent;
• and
• (g) directing the trickle bed effluent to a separator to produce the hydrogen-rich recycle gas stream for use in step (f) or (f′) and a liquid product.