Abstract: An one dimensional heterogeneous model for describing selective oxidation of butane to maleic anhydride over a domestic commercial VPO catalyst in the riser of a CFB(circulating fluidized bed)system and a bubbling bed model for the regeneration of the catalyst in the fluidized bed of this CFB reactor system are developed,respectively,to preliminarily explore controlling strategy of the spatial separation catalytic cycle which combines selective oxidation of n -butane and regeneration of the catalyst.Simulation results show that based on the regeneration kinetics of the catalyst,properly raising the reoxidation temperature of the catalyst in the fluidized bed reactor either can obviously improve the performance of the system or can reduce the solid flux and hence the energy consumption.Part I of this paper presents the models of the CFB system and computation method.