Insight into the true role of hydrogen-carbonate species in CO oxidation over Pd/Al2O3 catalyst using SSITKA-transmission IR technique

The powerful combination of steady state isotopic transient kinetic analysis (SSITKA) and operando infrared spectroscopy (IR) was applied to study the CO oxidation reaction on Pd-supported Al2O3 catalyst at low tem-perature. The aim was to reveal the true role of hydrogen-carbonate species in the reaction mechanism. The SSITKA-IR experiments, conducted in presence and absence of CO2 in the gas feed, have confirmed that hydrogen-carbonate species behave as spectator species in the reaction. Its formation was due to re-adsorption of the CO2 product itself on the alumina surface as confirmed by the direct 12CO2/13CO2 exchange observed on the bare support.