On the importance of nanocrystalline gold for Au/CeO2 water–gas shift catalysts

The purpose of the research described in this paper was to assess the importance of nanocrystalline gold on the water–gas shift (WGS) activities of Au/CeO2 catalysts. A series of Au/CeO2 catalysts with gold loadings up to 8.3 wt% and average gold crystallite sizes ranging from 4 to 7 nm was prepared using the deposition-precipitation method. Gold was leached from one of these materials using a procedure that has been reported to remove nanocrystalline gold. We report two key observations: (1) Reaction rates for catalysts before leaching were significantly higher than those for the catalysts after leaching, and (2) estimated turnover frequencies for the unleached catalysts were higher than those for the leached catalysts. The results emphasize the importance of nanocrystalline gold, at least for the WGS reaction.