Hydrocracking processes having an enhanced efficiency of hydrogen utilization

摘要

A hydrocrackate from a hydrocracking zone operating under hydrocracking conditions is separated into at least one liquid phase and a separated vapor phase wherein the separated vapor phase has a greater concentration of hydrogen than the minimum concentration of hydrogen in the vapor phase in the hydrocracking zone. At least a portion of the separated vapor phase is contacted with the feed side of a polymeric membrane selective to the permeation of hydrogen as compared to the permeation of methane, and the opposite side of the polymeric membrane is maintained at a pressure sufficiently below the pressure at the feed side of the polymeric membrane to permeate hydrogen to the opposite side of the polymeric membrane and to provide a hydrogen permeate having a concentration of hydrogen greater than the concentration of hydrogen in the separated vapor phase and greater than the concentration of hydrogen in the hydrogen feed gas. The hydrogen permeate is compressed and recycled to the hydrocracking zone.