FLUID CATALYTIC CRACKING CATALYST FOR REFORMULATED GASOLINES - KINETIC MODELING

Changes of the relative importance of intradiffusion on USY zeolite cr ystals were studied as a way of affecting selectivity of catalytic cra cking reactions. Zeolite crystals were synthesized (Si/Al = 2.4), acti vated and stabilized using ion exchange and steam calcination to obtai n USSY (Ultra Stable Submicron Y) zeolites. After the activation the z eolites were pelletized (45-60 mu m particles). USSYs were tested in a novel Riser Simulator. Results obtained show that total aromatics (BT X), benzene, C-4 olefins, and coke were significantly affected with th e change of zeolite crystal sizes. Gasolines produced with USSY zeolit es contain less aromatics and particularly lower benzene levels. Exper imental results were analyzed with a model including several lumps: un converted gas oil, gasoline, light gases, and coke. This model also ac counts for catalyst deactivation as a function of coke on catalyst. Va rious kinetic parameters were determined with their corresponding span s for the 95% level of confidence.