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-SnO, 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

Response of a catalytic reaction to periodic variation of the CO pressure: IncreasedCO2production and dynamic phase transition

“…One way to perturb the catalytic oxidation process in order to increase the CO 2 production is by switching the external pressure back and forth across the discontinuous transition y 2 (k) [5,6,7,8,9]. It has been shown that when the ZGB system without desorption is quickly oscillated between the low and high θ CO phases by a periodic variation of the external pressure, there is considerable enhancement of the catalytic activity [13,14].…”

Periodic Forcing of NO Reduction on a Pt(100) Surface

“…Positive results were in fact reported in a number of studies conducted typically under atmospheric pressure conditions [6][7][8][9][10]. Under these conditions mass and heat transfer plays a dominant role contrary to the low pressure ( p < 10 −3 mbar) single crystal experiments in which periodic forcing was also investigated.…”

“…Non-stationary reaction conditions may im-prove the yield and selectivity of reactions or reduce energy consumption as compared to stationary conditions [4][5][6]. oxidation of CO and unburned hydrocarbons as well as NO reduction [6][7][8][9][10]. In heterogeneous catalysis experimental studies with periodic forcing focused on the reactions of the automotive catalytic converter, i.e.…”

Dynamic response of an irreversible catalytic reaction to periodic variation of the reactant’s pressure

“…[9][10][11][12][13] In heterogeneous catalysis, periodic forcing has mostly been applied to reactions which play a role in the automotive catalytic converter, and in some cases substantial increases of the efficiency have been reported. [10][11][12][13] Periodic forcing experiments have been conducted in catalytic CO oxidation under high-pressure conditions (pϾ1 mbar). 11,15 Single crystal experiments have been performed for catalytic CO oxidation on Pt͑100͒ and Pt͑110͒.…”