Abstract: The present invention is a catalytic hydrocracking process which minimizes the fouling of the process unit with 11.sup.+ ring heavy polynuclear aromatic compounds by means of hydrogenating and converting at least a portion or slipstream of the hydrocarbon effluent from the hydrocracking zone containing trace quantities of 11.sup.+ ring heavy polynuclear aromatic compounds in a 11.sup.+ ring heavy polynuclear aromatic compound conversion zone containing a hydrogenation catalyst having a hydrogenation component at hydrogenation conditions to selectively reduce the concentration of 11.sup.+ ring heavy polynuclear aromatic compounds before the hydrocracking zone effluent is cooled below about 400.degree. F. At least a portion of the effluent from the 11.sup.+ ring heavy polynuclear aromatic compound conversion zone is cooled and separated to produce at least a portion of the unconverted recycle stream.

Abstract: A catalytic hydrocracking process which minimizes the fouling of the process unit with 11.sup.+ ring heavy polynuclear aromatic compounds by means of partially condensing the hydrocarbon effluent from the hydrocracking zone to produce an unconverted hydrocarbon stream comprising trace quantities of 11.sup.+ ring heavy polynuclear aromatic compounds and contacting the unconverted hydrocarbon stream with an adsorbent which selectively retains the 11.sup.+ ring heavy polynuclear aromatic compounds before the unconverted hydrocarbon stream is recycled to the hydrocracking zone.

Abstract: A catalytic hydrocracking process which minimizes the fouling of the process unit with 11.sup.+ ring heavy polynuclear aromatic compounds by means of hydrogenating and converting at least a portion of the recycle hydrocarbon liquid containing trace quantities of 11.sup.+ ring heavy polynuclear aromatic compounds in a 11.sup.+ ring heavy polynuclear aromatic compound conversion zone containing a zeolite hydrogenation catalyst having pore openings in the range from about 8 to about 15 Angstroms, a hydrogenation component and an intercalated clay component at hydrogenation conditions to selectively reduce the concentration of 11.sup.+ ring heavy polynuclear aromatic compounds.

Abstract: A catalytic hydrocracking process which comprises: (a) contacting a hydrocarbonaceous feedstock having a propensity to form 11.sup.+ ring heavy polynuclear aromatic compounds and a liquid recycle stream in a hydrocracking zone with added hydrogen and a metal promoted hydrocracking catalyst at elevated temperature and pressure sufficient to convert a substantial portion of the feedstock to lower boiling hydrocarbon products; (b) partially condensing the hydrocarbon effluent from the hydrocracking zone to produce a gaseous hydrocarbon stream comprising hydrogen, and an unconverted hydrocarbon stream having components boiling above about 400.degree. F. (204.degree. C.) and comprising trace quantities of 11.sup.

Abstract: A catalytic hydrocracking process which comprises: (a) contacting a hydrocarbonaceous feedstock having a propensity to form 11.sup.+ ring heavy polynuclear aromatic compounds and a liquid recycle stream in a hydrocracking zone with added hydrogen and a metal promoted hydrocracking catalyst at elevated temperature and pressure sufficient to gain a substantial conversion to lower boiling products; (b) partially condensing the hydrocarbon effluent from the hydrocracking zone and separating the same into a lower boiling hydrocarbon product stream and an unconverted hydrocarbon stream boiling above about 400.degree. F. (204.degree. C.) and comprising trace quantities of 11.sup.+ ring heavy polynuclear aromatic compounds; (c) introducing at least a portion of the unconverted hydrocarbon stream boiling above about 400.degree. F. (204.degree. C.) and comprising trace quantities of 11.sup.+ ring heavy polynuclear aromatic compounds into a 11.sup.

Abstract: A catalytic hydrocracking process which comprises (a) introducing a reduced crude into a fractionation zone to produce a vacuum gas oil stream having a propensity to form polynuclear aromatic compounds in a hydrocracking zone and a slop wax stream; (b) contacting the vacuum gas oil stream in a hydrocracking zone with added hydrogen and a metal promoted hydrocracking catalyst at elevated temperature and pressure sufficient to gain a substantial conversion to lower boiling products; (c) partially condensing the hydrocarbon effluent from the hydrocracking zone and separating the same into a low boiling hydrocarbon product stream and an unconverted hydrocarbon stream boiling above about 650.degree. F. (343.degree. C.