Abstract: The mass fraction of iron in the raw material in the 2.2Mt/a catalytic cracking unit using MIP-CGP process in a petrochemical company reached 8.2μg/g due to the influence of the upstream atmospheric and vacuum distillation unit. The activity of catalyst decrease and the iron mass fraction of equilibrium catalyst exceeded 0.6%. The catalyst system showed the phenomenon of iron contamination of the catalyst: such as the formation of "iron nodules" on the surface of the catalyst, the catalyst consumption increase, the specific surface area of the catalyst was reduced to 102 m²/g, the average particle size was increased to 78 μm, the fluidization effect of the reaction-regeneration system was worse, and the product yield was reduced. In order to solve the problem of iron contamination in the catalyst, anti-iron additives were used. After the addition of anti-iron additives, the pores at the grooves of the anti-iron additives were covered by "iron nodules", in which the iron mass fraction was as high as 13.22%, which could effectively alleviate the iron contamination of the catalyst.

Key words: MIP-CGP, fluid catalytic cracking, iron contamination, anti-iron additives, scanning electron microscope