Prediction of the performance of coked and regenerated fluid catalytic cracking catalyst mixtures. Opportunities for process flexibility

The performance of a coked fluid catalytic cracking catalyst (0.56 wt % cok e on catalyst) has been determined and compared to that of a fully regenera ted catalyst by cracking of a Hydrowax feedstock in the microriser equipmen t. The activity of the coked catalyst is lower, but still significant, and the selectivity is similar to that of the regenerated catalyst. A kinetic a nalysis shows that the activity of the coked catalyst is constant: it is no t further decreased by additional coke deposition. The kinetic model can be used to predict the performance of a mixture of the coked and regenerated catalyst because it behaves like a physical mixture of the two catalysts Th e application of such mixtures in industrial operation, as in the recently developed UOP X-design, increases process flexibility; the temperature of t he stripper and the riser inlet and. the associated reaction selectivities can be changed without changing the overall heat balance of the process.