Active Au Species During the Low-Temperature Water Gas Shift Reaction on Au/CeO2: A Time-Resolved Operando XAS and DRIFTS Study

Abstract

Operando XAS measurements in the near (XANES) and the extended (EXAFS) Au LIII edge as well as in situ diffuse reflectance FTIR (DRIFTS) spectroscopy were employed in combination with kinetic measurements in a further attempt to identify the nature of the active Au species responsible for the high activity of Au/CeO2 catalyst in the low-temperature water gas shift (LT-WGS) reaction. The changes in the reaction behavior during the LT-WGS were followed at 180 °C for different initial states of the catalyst, prepared by either reducing or oxidizing pretreatments at different temperatures. Findings from kinetic and deactivation measurements were correlated with experimental data on the Au particle size, the Au oxidation state, and the CO-Au adsorption properties directly after different pretreatments and during the subsequent LT-WGS reaction obtained by operando/in situ spectroscopy measurements. The combined experimental results show that the use of different pretreatments can significantly influence the ele...