Study of the Performance of Catalysts for Catalytic Cracking by Applying a Lump-Based Kinetic Model

In catalytic cracking, catalysts selection is not a trivial task since a catalyst should exhibit a good hydrothermal stability as well as product distributions and qualities according to the necessities of the refinery. Cracking experiments at the bench scale in a fluidized confined-bed reactor at 789 K in the catalyst to oil range of 3.0−7.5 g/g using two industrial feeds have coupled to a five-lump kinetic model for a quantitative study of a set of cracking catalysts. To a gain insight into the catalysts performance, the assessment of raw rate coefficients has been complemented with a reaction pathways analysis. Primary cracking reactions are 1 order of magnitude higher than secondary ones, the gasoil to gasoline conversion being the fastest reaction. Up to 23% of the formed gasoline may undergo secondary cracking, more than 90% of it ending up in LPG. At the investigated conditions, coke formation is practically fully formed out of gasoline via secondary reactions and not from the gasoil. Cracking results are in concordance with catalyst properties, i.e., specific surface areas, and catalyst composition, e.g., the rate of secondary cracking of gasoline to LPG decreases with the zeolite and rare earths content.