Describe the kinetic models used for FCC riser simulation.

FCC kinetic models: Lumped models - 3-lump (gas oil, gasoline, gas+coke), 5-lump, 10-lump, or more. Each lump has cracking rate constant following Arrhenius temperature dependence. Reactions: primary cracking (VGO to products), secondary cracking (gasoline to gas/coke), hydrogen transfer, isomerization. Catalyst deactivation - activity decays exponentially with coke on catalyst, time-on-stream function. Yield prediction - material balances with kinetic expressions. Advanced models include: feed characterization (paraffins, naphthenes, aromatics), molecular-level simulation (structure-oriented lumping), and microactivity test (MAT) correlation. Riser hydrodynamics modeled as plug flow with catalyst slip. Parameters fitted to pilot/commercial data. Models used for yield prediction, catalyst evaluation, and unit optimization.