A fully predictive core-annulus hydrodynamic model for tile gas and solids flow structure in circulating fluidized bed (CFB) risers is coupled with first-order heterogeneous reaction kinetics to simulate the decompositon of ozone in a CFB catalytic reactor. Excellent agreement between the simulation and published experimental data for ozone decomposition in units of differing scale is obtained through the use of a single adjustable parameter, namely, the core-to-annulus gas mass transfer coefficient. The gas-solids contacting efficiency parameter introduced in other models of this reaction is not required. The simulation is extended to consider thr oxidation coupling of methane in a CFB catalytic reactor.