Deactivation kinetic models for the fluid catalytic cracking (FCC). A review
Tomás Cordero‐Lanzac, Javier Bilbao
Abstract
• The FCC unit is key to meet the sustainability goals of the refinery of the future. • Kinetic modeling of deactivation should be a priority research target. • Coke deposition is the main cause of the fast catalyst deactivation. • The experimental methodology for modeling should reproduce the industrial unit. • A selective deactivation model provides a better description of the real phenomena. Fluidized catalytic cracking (FCC) units play an important role in the strategic goals of the oil industry and in its evolution towards the production of fuels and chemicals with less environmental impact. The fast catalyst deactivation conditions the design and operation of the reactor and regenerator sections of these units. This review describes the characteristics and historical evolution of the FCC process (main cause), paying special attention to the origins of deactivation, the mechanism of coke formation, and the consideration of catalyst deactivation in kinetic modeling. A summary of deactivation kinetic models described in the literature for catalytic processes are included herein due to their relevance and application to the FCC process. The deactivation kinetic equations used in the modeling of the riser reactor (mostly empirical) are presented. These equations have been incorporated in non-selective deactivation models (the most commonly used) and selective ones. The latter considers the heterogeneity of the catalyst and/or the different influence of deactivation on the individual steps of the reaction network of cracking. In a final discussion, we have analyzed the causes that motivated the simplifications in the kinetic models of catalyst deactivation during the FCC process. Among them, one can highlight the different causes of deactivation, the heterogeneity of the coke and active sites in the catalyst, and the experimental difficulty to reproduce the riser reactor conditions. Moreover, simplicity in the models is also a requirement for the application of models to simulate FCC units at refinery level. In the recommendations to improve kinetic modeling, the use of selective deactivation models is of priority interest.