Transient gas mixing tests in a gas-solid fluidized bed are analyzed with a dispersive plug flow model from the bubbling to the turbulent regime, and with the two-phase model of van Deemter. It is shown that dispersion fluctuations can also be used besides pressure fluctuations or capacitance probes to characterize the transition between the bubbling and the turbulent regime. Furthermore, the gas Peclet number in the turbulent regime is correlated ih terms of the operating parameters, the bed diameter and the particles and gas properties as : Pe = 7.10(-2)Ar(0.32)delta(-0.4). The cross-flow mass transfer coefficient alpha(12) of the two-phase model of van Deemter in the bubbling and the turbulent regimes is correlated in terms of the height of a transfer unit as : U/alpha(12) = 0.613Sc(-0.37) The parameters from both correlations are coupled with the kinetics of an industrial catalyst to model the performance of a catalytic combustor.