A comparative study of the deactivation mechanisms of the Au/CeO2 catalyst for water–gas shift under steady-state and shutdown/start-up conditions in realistic reformate

The deactivation mechanisms of the Au/CeO2 catalyst in steady-state and shutdown/start-up WGS reactions were investigated in realistic reformate at 250 °C. Catalyst deactivation due to sintering was excluded. After steady-state operation, the original activity was not recovered by removing the deposited carbonate species. The influences of the component gases of realistic reformate on the activity suggest that loss of the Au–CeO2 interaction caused by the reducing H2 and CO is the main reason for catalyst deactivation. Under the shutdown/start-up condition, the catalyst suffered more drastic deactivation, although it underwent a lesser degree of reduction. A good correlation between the extent of deactivation and the amount of the carbonate species indicates that catalyst deactivation is mainly caused by enhanced formation of the carbonate species, especially through a combined effect of CO2 and H2O, during the low-temperature shutdown and start-up steps. The implications of these findings for improved applications of the Au/CeO2 catalyst in WGS are indicated.

The deactivation behavior of the Au/CeO2 catalyst in steady-state and shutdown/start-up WGS reactions was investigated. The loss of Au–CeO2 interaction by reduction and carbonate deposition were, respectively, identified as accounting for catalyst deactivation under these situations.Figure optionsDownload high-quality image (182 K)Download as PowerPoint slideHighlights
► Deactivation mechanisms of the Au/CeO2 catalyst in WGS reaction were investigated.
► Effects of component gases of realistic reformate on the activity were discriminated.
► Deactivation in steady-state operation is mainly caused by the loss of Au–CeO2 interaction by reduction.
► Deactivation in shutdown/start-up operation is attributed to carbonate deposition.
► Shutdown and start-up in H2O or H2 may effectively avoid catalyst deactivation.