A four-phase model for fluidized-bed catalytic reactors is developed. The bed is divided into four phases, i.e., bubble, cloud-wake, emulsion upflow, and emulsion downflow phases. In the model, gas back mixing in the emulsion phase and gas interchange as well as gas cross flow between phases are all considered. Model predictions are shown to compare well with various published experimental data on both axial concentration profiles and overall conversions. Parameters effects on the reaction performance were also illustrated. It was found that neglecting cross flow will result in 13% lower on the predicted conversion.