Fluid catalytic cracking process for heavy oil

A process for the fluid catalytic cracking of a heavy-fraction oil, which comprises

• contacting the oil with a catalyst mixture consisting of 60 to 95 wt % of a base cracking catalyst containing an ultra stable Y-type zeolite having a crystal lattice constant of greater than 24.55 Å to 24.60 Å, and less than 0.5 wt % of rare-earth metal oxide, and 5 to 40 wt % of an additive containing a shape-selective zeolite;
• said additive having a bulk density of 0.5 to 1.0 g/ml, an average particle diameter of 50 to 90 microns, a surface area of 10 to 200 m2/g and a pore volume of 0.01 to 0.3 ml/g;
• wherein said contacting takes place in a fluid catalytic cracking apparatus having a regeneration zone, a down flow reaction zone, a separation zone and a stripping zone, and under conditions that the reaction zone outlet temperature is in the range of 580 to 630° C., the catalyst/oil ratio is in the range of 15 to 40 wt/wt, and the contact time of hydrocarbons in the reaction zone is in the range of 0.1 to 1.0 sec.