Abstract
A relatively simple two-phase model for the non-isothermal fluidized bed catalytic reactor with consecutive exothermic reactions has been used to investigate the complex oscillatory behaviour of this industrially important unit. Relaxation oscillations are produced by distortion of limit cycles which have fast and slow motion in the phase space. The new type of period-adding bifurcation has been uncovered, analysed and is shown to generate periodic bursting with high periodicity. The period-adding mechanism presented is classified as a third kind of period-adding. The complex oscillatory trajectory is conjectured to terminate by a boundary crisis.