Correlating spatially resolved catalysis and Raman spectroscopy during CO oxidation over Cu/CeO2 catalysts

Abstract

Spatially resolved analysis allows for the development of accurate structure – property correlations in regimes of high catalytic conversion. We report on the novel combination of a compact profile reactor with IR spectroscopy for spatially resolved gas-phase analysis and with Raman spectroscopy for spatially resolved structural analysis. The potential of this combined approach is illustrated for the CO oxidation over low-loaded Cu/CeO₂ catalysts at atmospheric pressure but the use of higher pressures is feasible. Spatially resolved operando Raman spectroscopy of Cu/CeO₂ at 150 °C reveals structural dynamics directly correlated with the catalytic conversion. With increasing conversion an increase in the consumption of surface lattice oxygen is observed which is accompanied by the formation of oxygen vacancies and ceria reduction. Our mechanistic findings demonstrate the participation of the ceria support in the CO oxidation at high conversions, fully consistent with a Mars-van-Krevelen mechanism. The presented setup provides high versatility for detailed mechanistic analysis of catalysts as a function of changing gas environments and their influence on the structural dynamics.