Rate enhancements and quasi-periodic dynamics during forced concentration cycling of CO and O2 over supported Pt---SnO2

Abstract

Forced reactant cycling of carbon monoxide-nitrogen and oxygen-nitrogen streams over Pt---SnO2 in a differential reactor results in enhancements of the reaction rate of up to 9 times that of the optimal steady state. Dynamic features common to periodically forced reaction systems were experimentally observed. In addition, quasi-periodic behaviour under forced concentration cycling was also observed. Transient response experiments combined with see-through FTIR analysis confirm an underlying Langmuir-Hinshelwood-type mechanism. Spectral analysis of the quasi-periodic patterns identified at least three time constants of different orders of magnitude. The nature of the patterns also indicated a reaction mechanism which included one or more "reservoirs" of reactants and/or reaction intermediates.