INTEGRATED HYDROPROCESSING SCHEME FOR PRODUCTION OF PREMIUM QUALITY DISTILLATES AND LUBRICANTS

An integrated refining scheme is disclosed for hydroprocessing high boiling fractions such as gas oil and catalytically cracked cycle oils to produce premium quality distillates, especially jet fuels and naphthas suitable for reforming into high octane gasoline. The integrated hydroprocessing comprises a first stage hydrocracking step employing an aromatic selective hydrocracking catalyst based on a large pore size acidic component such as amorphous alumina or silica alumina or a large pore size zeolite such as zeolite X or zeolite Y. The hydrocracking may be operated either in a naphtha directing mode under conditions of moderate to high severity or under conditions of low to moderate severity to produce a relatively higher proportion of product boiling in the middle distillate range. The unconverted fraction from the hydrocracking step is passed to a second step in which it is hydroprocessed over a zeolite beta catalyst with additional hydrogenation-dehydrogenation functionality. In this stage, the paraffins remaining in the feed are converted by the zeolite beta into isoparaffins and conditions may be controlled to favor hydroisomerization over hydrocracking so as to increase the yield of middle distillate product, especially of highly isoparaffinic jet fuels and diesel fuel.