Development of a kinetic model for FCC valid from ultra-short residence times

Experimental data from Hydrowax cracking using the microriser equipment hav e been used to develop a kinetic model that adequately describes the experi mental data from 0.05 to 5 s residence time. To account for different time scales of the reactions, different activity functions were used for coke fo rmation and for conversion to the other products. The activity for coke for mation was described by an exponentially decreasing function of the residen ce time with a very short characteristic time of 0.02 s. The activity for f ormation of the other products was also described by an exponentially decre asing function, in this case of the coke content of the catalyst. The model was used to predict the residual activity of the catalyst in a se cond experiment with fresh Hydrowax feedstock. Using the assumption that in the second run no further deactivation of the catalyst took place, the mod el predictions agreed well with the experimental data. The applicability of the model to data from other feedstocks, a hydrotreate d flashed distillate and a vacuum gas oil, was successfully demonstrated.