CRACKING CATALYST DEACTIVATION BY NICKEL AND VANADIUM CONTAMINANTS

The unsteady-state pulse technique has been applied to the catalytic cracking of gas oils with several commercial catalysts. Experimental runs were performed in a pulse microcatalytic fixed bed reactor to closely mimic the short contact times of commercial fluid catalytic cracking (FCC) riser reactors. Equilibrium catalyst was simulated by steaming in a fluidized bed, artificial impregnation with metal naphthenates under vacuum, and calcination. Analytical techniques were used to confirm the effectiveness of the artificial aging method. The poisoning effects of nickel and vanadium have been demonstrated on different catalysts through the changes obtained in overall conversions and product selectivities. The kinetic constants evaluated for a three- and a five-lump model clearly showed a decreasing trend, with the increment of metal loading being from 0 to 5000 ppm nickel equivalent. Moreover, the activation energies calculated presented a consistent tendency, decreasing with increasing metal concentration. © 1990, American Chemical Society. All rights reserved.