Comparison of stationary and transient kinetic methods in determining the rate of surface exchange reaction between molecular oxygen and MIEC perovskite

The kinetic parameters of the reaction of nonstoichiometric oxide Ba0.5Sr0.5Co0.75Fe0.2Mo0.05O3-delta with molecular oxygen were determined by two independent methods: the steady-state oxygen permeability of the hollow fiber membrane and the transient kinetics of re-equilibration. To analyze the results, we used mathematical models that take into account the inhomogeneity of conditions in the relaxation reactor and gas flows in the tubular membrane. For a correct comparison of the two methods, the same formulation of the surface reaction rate was used in both models, taking into account the dependence of the reaction rate constant on oxide stoichiometry. As a result, a quantitative agreement was obtained between the values of the equilibrium exchange rate R-0, including its activation energy, and the dependence on the oxygen partial pressure.

Automated summary

The kinetic parameters of a reaction between a nonstoichiometric oxide and molecular oxygen were determined using two independent methods, steady-state oxygen permeability and transient kinetics. Mathematical models were used to analyze the results, taking into account the inhomogeneity of conditions and gas flows. The results showed a quantitative agreement between the two methods, considering the dependence of the reaction rate constant on oxide stoichiometry.