Method of hydrocracking paraffins emanating from the Fischer-Tropsch process using catalysts based on H-Y zeolite

A method of hydrocracking a charge emanating from the Fisher-Tropsch process, said charge comprising unsaturated and oxygenated hydrocarbon molecules, said method comprising:

• (a) reacting hydrogen with the charge in contact with a first catalyst in a first reaction zone, the first catalyst comprising at least one matrix consisting essentially of alumina and at least one first hydro-dehydrogenation component to remove unsaturated and oxygenated hydrocarbon molecules from the charge;
• (b) contacting the resultant effluent from the first reaction zone with a second catalyst in a second reaction zone, the second catalyst comprising:
• 20 to 97% by weight of at least one matrix;
• 3 to 80% by weight of at least one Y zeolite in hydrogen form,
• said Y zeolite having a SiO.sub.2 :Al.sub.2 O.sub.3 molar ratio of over 4.5:1, a sodium content of less than 1% by weight determined on a zeolite calcined at 1100.degree. C., an a.sub.0 crystal parameter of the elemental mesh of less than 24.70.times.10.sup.-10 m;
• and a specific surface area determined by the BET method of over 400 m.sup.2.g.sup.-1 ;
• and at least one second hydro-dehydrogenation component, to produce a hydrocracked product.