A COMPARISON OF LABORATORY DEACTIVATION METHODS FOR FCC CATALYSTS

Two different methods for laboratory deactivation of FCC catalysts have been compared to deactivation in a commercial FCC unit. The two laboratory methods investigated were: (i) metals impregnation by an incipient wetness method according to Mitchell followed by steaming, and (ii) cyclic impregnation and deactivation in a cyclic deactivation unit (CDU). The cyclic deactivation method consists of cycles with cracking of metal spiked feed, stripping and regeneration in a fluidized bed reactor. An apparatus for cyclic deactivation is described. To find the better laboratory deactivation method the three deactivated catalyst samples were chemically and physically characterized and micro activity tested (MAT) with North Sea atmospheric residue as feed. It was found that cyclic deactivation gave a better simulation of the equilibrium catalyst from the FCC unit (ECAT) than was the case for Mitchell impregnation and steaming. The metals are still more active for dehydrogenation reactions following cyclic deactivation than metals are in the ECAT, although cyclic deactivation represents an improvement compared with impregnation and steaming. It was found also that fresh catalyst particles in ECAT contribute significantly to product distribution and quality, making 'perfect' simulation of ECAT with laboratory deactivated samples consisting of uniformly deactivated particles very difficult, Significant differences were not found in metal distribution across the catalyst particles resulting from the different deactivation procedures, It was found that vanadium migrates more easily through the catalyst particles than nickel during the deactivation.