Modelling complex transient oscillations for the BZ reaction in a batch reactor

The recent observations of transient complex oscillations in the Belousov-Zhabotinsky (BZ) reaction in a batch reactor are confirmed and an attempt is made to model this behavior using the Gyorgyi-Field mechanism (an extension of the classic Field-Koros-Noyes model). It is seen that the concentration of bromomalonic acid plays an important role, acting somewhat like a ''slowly-varying parameter,'' causing the system to sweep through a region of oscillatory response even in the absence of reactant consumption. Complex behavior is not observed in the model if the usual ''pre-equilibrium'' assumption in made for the intermediate species BrO2 but does arise if a full steady-state approximation is applied to this radical. These results may bring into question some assumptions made in the usual treatment of the cerium-catalyzed BZ system in closed reactors. (C) 1997 American Institute of Physics.