Process for fluid catalytic cracking of distillation residual oils

Abstract

A process for fluid catalytic cracking of a starting oil selected from the group consisting of a distillation residual oil, a solvent deasphalted oil derived therefrom and a hydrodesulfurized oil derived therefrom, which comprises withdrawing a part of catalyst particles circulating through a fluid catalytic cracking unit, sending the withdrawn catalyst particles by means of a carrier fluid selected from the group consisting of air, nitrogen, steam and the mixtures thereof at a rate of 0.01 to 100 meters/second in a particle concentration of 0.01 to 500 g/liter to a high gradient magnetic separator in which a ferromagnetic matrix is placed in a uniform high magnetic field to generate a high magnetic gradient around the matrix, thereby separating the withdrawn catalyst particles into a group of particles rendered magnetic by the deposition of at least one metal selected from the group consisting of nickel, vanadium, iron and copper which are contained in the starting oil and a group of non-magnetic particles; and returning the non-magnetic particles to the fluid catalytic cracking unit for re-use.