Evaluating factors that affect FCC stripper behaviour in a laboratory fluidised-bed reactor

Abstract

An experimental protocol based on a laboratory fluidised-bed reactor has been developed to determine how the yield and composition of coke and the associated catalyst surface area vary as a function of stripper conditions in fluid catalytic cracking (FCC). In this study, it is demonstrated that coke from the fluidised-bed reactor prior to stripping and from an actual FCC riser unit are very similar compositionally, including the amounts of soft (chloroform-soluble) coke physically entrapped within the catalyst pore structure and only released after demineralisation that ultimately control the final coke yields. It has also been confirmed that hard coke from both actual feeds and a model compound, n -nonene used to simulate the formation of catalytic coke, are all highly aromatic after short stripping periods. Further, transferring the deactivated catalyst from the fluidised-bed reactor after very short stripping times to other reactors has provided a means to ascertain precisely the influence of gas flow rate on stripping. Finally, the stripping behaviour of a selection of commercial FCC catalysts has been compared in the fluidised-bed reactor.