| Abstract: | Vanadium and nickel have been identified as the major poisons that lead to the deactivation of cracking catalysts. These metals can be demetallized by a multistage process involving gas solid non-catalytic reactions in porous particles. Mathematical models for predicting the removal rate of vanadium when diffusion, reaction, and reaction and diffusion are controlling have been developed. It is generally accepted that vanadium is deposited on specific sites in the interior of the catalyst. This is verified since a diffusion controlled model for the removal of vanadium is in close agreement with experimental results. The parameters of the diffusion controlled model were estimated by constrained nonlinear regression. A total of five lumped mass transfer parameters for vanadium removal were determined using data from a laboratory demetallization unit. These parameters were then used to predict vanadium removal and compared with experiment. |
