(180b) A Deep Dive into Iron Contamination on Fluid Catalytic Cracking Catalysts

Fluid catalytic cracking (FCC) utilizes a solid, fluidized catalyst, mainly made up of silica and alumina. There are many components in an FCC catalyst including amorphous matrix material, zeolite Y crystal, metals trapping ingredients, binders, and other additives. The FCC catalyst is prone to deactivation and unwanted effects by a number of contaminants that come into the FCC via the crude oil. Contaminants of concern include nickel, vanadium, sodium, and iron. Nickel acts as a dehydrogenation catalyst and leads to higher hydrogen and coke during FCC unit operation. Vanadium directly attacks the zeolite active sites of the FCC catalyst. Sodium neutralizes the acid sites of the FCC catalyst rendering its activity lower. Iron has many different facets to its contamination profile and they will be discussed in this presentation.

Iron comes in with the crude oil. It is found in especially high concentrations in tight oils, so has become more of a concern in the United States in recent years. Iron participates in a number of mechanisms in an FCC unit including mild dehydrogenation, CO promotion in the regenerator, and acts as in inverse SOx additive, resulting in higher SOx emissions from the FCC unit. More importantly, iron can block the surface pores of the catalyst, which prevents FCC feed from entering the catalyst particles. This will directly result in lower conversion and higher slurry yields coming off the FCC. This latter phenomenon has been studied in detail and will be presented here. The effect of various technologies and manufacturing techniques will be discussed. Case studies involving refinery operations will be presented, some of which showing very extreme effects on the FCC catalyst. The source of the problem and the mitigation steps to curb iron poisoning of FCC catalyst will be presented in this lecture.