FAST CATALYTIC CRACKING OF HEAVY GAS OILS - MODELING COKE DEACTIVATION

An unsteady-state pulse technique has been used to evaluate kinetic parameters for catalytic cracking of heavy gas oil with steamed commercial catalysts. The method closely mimic conditions of commercial FCC riser reactors. The experimental results obtained at a catalyst time-on-stream of under 20 s allowed the evaluation of activation energies and kinetic constants for gas oil decomposition into gasoline and light gas plus coke, as a whole, as well as for individual groups: paraffins, naphthenes, and aromatics. Two models were considered in the present study: (a) a three-lump model featuring gas oil, gasoline, and gas plus coke; (b) a five-lump model, where gas oil was split into paraffins, naphthenes, and aromatics. It was found that the catalyst deactivation due to coke formation, for contact times under 20 s, can be represented by both an exponential decay function and a power decay function with an average exponent of 0.1-0.2. © 1990, American Chemical Society. All rights reserved.