Hydrocracking process using a catalyst selective for making middle distillates

A hydrocracking process for producing middle distillate products which comprises contacting a hydrocarbon feedstock with a hydrocracking catalyst in the presence of added hydrogen under hydrocracking conditions, wherein said catalyst comprises a support containing a zeolite having a unit cell size between 24.20 and 24.35 angstroms and a dispersion of silica-alumina in an alumina matrix and said catalyst is prepared by the process comprising:

• (a) extruding a mixture of a dispersion of silica-alumina in an alumina matrix and a crystalline aluminosilicate zeolite having cracking activity to form extrudates, wherein said crystalline aluminosilicate zeolite has a unit cell size between 24.40 and 24.95 angstroms and is selected from the group consisting of Y zeolites, modified Y zeolites, X zeolites and modified X zeolites;
• (b) calcining said extrudates in the presence of steam at a water vapor partial pressure greater than about 5.0 psia under conditions such that the unit cell size of said crystalline aluminosilicate zeolite is reduced to a value between about 24.20 and 24.35 angstroms;
• and
• (c) impregnating said calcined extrudates with at least one hydrogenation component.