engleski

The evaluation of FCC catalysts with microactivity procedure

The FCC process is the major refinery route for upgrading the value of vacuum distillates and makes a significant contribution to the gasoline pool which is now being influenced by lead phase- out requirements. There is, correspondingly, a large economic incentive to improve and optimise the catalysts in this process. The assessment of catalytic selectivity is of major importance to refiners because it determines the preferred selective formation of desired products, with the suppression of unwanted by - products. In this paper the microactivity test MAT ASTM D 3907 was used to determine the activities and selectivities of three comercial FCC catalysts. The experiments were carried out in fixed bed reactor at temperature of 482 C and with vacuum gas oil, as standard FCC feedstock. The catalyst/oil ratio was adjusted (from 2.25 to 3.75) in order to very the reactor selectivity and procedure different conveersions. By use of the Simulated Distillation chromatographic procedure a quantitative assessment was made of ligh cycle oil yields, in addition to that of the gasoline. The chromatographic analysis of the gas phase products provides information on the C_3-C_4 hydrocarbon yields for different catalyst types, as an indication of the catalytic gasoline octane quality. The results obtained were used to generate the yield curves, which allow interpolation of the data and comparison of catalytic selectivities at constant conversions. The selectivity changes reflect the trends expected due to physical and chemical properties of the catalysts, especially rare-earth exchange level and unit-cell size.

FCC catalysts; Microactivity test; Selectivity

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