DEMETALATION CHEMISTRY - CONTROL OF VANADIUM ON FLUID CRACKING CATALYST

Some fraction (~13%) of the vanadium deposited on the regenerated equilibrium FCC catalyst in the FCC unit was readily removed from the catalyst matrix by a water wash. The vanadium removal was improved to ~28% by applying the reductive wash with an aqueous sulfur dioxide solution followed by the oxidative wash with an aqueous hydrogen peroxide solution to the same regenerated catalyst. A significant fraction of vanadium, 50-70%, was further removed by subjecting the same catalyst to the calcination step at higher temperatures (730-815 °C) before the reductive and oxidative washing scheme. The microactivity test results showed that the catalytic activity of the devanadated FCC equilibrium catalyst was remarkably rejuvenated. The improvement in the catalytic activity of the devanadated system is directly tied with the degree of vanadium removal. These results clearly suggest that the poisoning effect of the vanadium on the FCC catalyst can at least partially be reversed by removing vanadium from the metal-contaminated FCC catalyst by a simple calcination/ washing process. © 1990, American Chemical Society. All rights reserved.