Hydroprocessing light cycle oil in liquid-full reactors

摘要

A process for the hydroprocessing of a low-value light cycle oil (LCO) hydrocarbon feed to provide a high-value diesel-range product. The process comprises a hydrotreatment stage followed by a hydrocracking stage, each of which is conducted under liquid-full reaction conditions wherein substantially all the hydrogen supplied to the hydrotreating and hydrocracking reactions is dissolved in the liquid-phase hydrocarbon feed. Ammonia and optionally other gases formed during hydrotreatment are removed in a separation step prior to hydrocracking. The LCO feed is advantageously converted to diesel in high yield with little loss of hydrocarbon to naphtha.

主权项

1. A process for hydroprocessing a hydrocarbon feed, comprising:
(a) contacting the hydrocarbon feed with hydrogen and a first diluent to form a first liquid feed, wherein hydrogen is dissolved in said first liquid feed, and wherein the hydrocarbon feed is a light cycle oil (LCO) having a polyaromatic content greater than 25% by weight, a nitrogen content greater than 300 parts per million by weight (wppm), and a density greater than 890 kg/m3 at 15.6° C.; (b) contacting the first liquid feed mixture with a first catalyst in a first liquid-full reaction zone to produce a first effluent; (c) recycling a portion of the first effluent for use as all or part of the first diluent in step (a); (d) separating at least a portion of the first effluent not recycled in a separation zone into at least three fractions comprising: (i) a low boiling fraction comprising ammonia and optionally other gases, (ii) a diesel fraction comprising a diesel-range product having a density no more than 870 kg/m3 at 15.6° C., a polyaromatic content no more than 13% by weight, and a sulfur content no more than 60 wppm, and (iii) a high boiling fraction having a nitrogen content less than 100 wppm; (e) contacting at least a portion of the high boiling fraction with hydrogen and a second diluent to produce a second liquid feed, wherein hydrogen is dissolved in said second liquid feed; (f) contacting the second liquid feed with a second catalyst in a second liquid-full reaction zone to produce a second effluent having a density less than 875 kg/m3 at 15.6° C. and a polyaromatic content less than 15% by weight; and (g) recycling a portion of the second effluent for use as all or part of the second diluent in step (e);
wherein the at least three fractions comprise a naphtha fraction, and the diesel fraction is at least 90% by volume based on the total volume of the diesel and naphtha fractions.