Hydrocracking process for a hydrocarbon stream

摘要

A process for transalkylating a coal tar stream is described. A coal tar stream is provided, and is fractionated to provide at least one hydrocarbon stream having polycyclic aromatics. The hydrocarbon stream is hydrotreated in a hydrotreating zone, and then hydrocracked in a hydrocracking zone. A light aromatics stream is added to the hydrocracking zone. The light aromatics stream comprises one or more light aromatics having a ratio of methyl/aromatic available position that is lower than a ratio of methyl/aromatic available position for the hydrotreated stream. The hydrocracked stream is transalkylated in the hydrocracking zone.

主权项

1. A process comprising:
providing a coal tar stream; fractionating the coal tar stream to provide at least one hydrocarbon stream having polycyclic aromatics; hydrotreating the hydrocarbon stream in a hydrotreating zone in the presence of a catalyst containing at least one group VIII metal and at least one group VI metal to remove sulfur, nitrogen, and metals and to saturate hydrocarbon with double or triple bonds; hydrocracking the hydrotreated stream in the presence of catalyst comprising amorphous silica-alumina bases or low-level zeolite bases combined with one or more group VIII or group VIB metal hydrogenating metal in a hydrocracking zone to crack the polycyclic aromatics to mono-aromatics and saturate mono-aromatics to cycloparaffins; adding a light aromatics stream to the hydrocracking zone; transalkylating the polycyclic aromatic with the aromatics in the light aromatics stream in the hydrocracking zone to provide a greater portion of xylenes in the effluent of the hydrocracking zone; feeding the effluent from the hydrocracking zone to a dehydrogenation zone to convert cycloparaffins to aromatics in the presence of a catalyst containing platinum, Pt—Re or Pt—Sn and alumina or chloride alumina; recycling a portion of the effluent of the dehydrogenation zone to the hydrocracking zone; and wherein the light aromatics stream comprises one or more light aromatics having a ratio of methyl/aromatic available position that is lower than a ratio of methyl/aromatic available position for the hydrotreated stream.