Investigation of the effect of the preparation method on the activity and stability of Au/CeZrO4 catalysts for the low temperature water gas shift reaction

The impact of the preparation method on the activity and stability of gold supported on ceria–zirconia low temperature water-gas shift (WGS) catalysts have been investigated. The influence of the gold deposition method, nature of the gold precursor, nature of the washing solution, drying method, Ce:Zr ratio of the support and sulfation of the support have been evaluated. The highest activity catalysts were obtained using a support with a Ce:Zr mole ratio 1:1, HAuCl4 as the gold precursor deposited via deposition precipitation using sodium carbonate as the precipitation agent and the catalyst washed with water or 0.1 M NH4OH solution. In addition, the drying used was found to be critical with drying under vacuum at room temperature found to be most effective.DRIFT spectra of CO adsorbed at room temperature over the range of catalysts synthesized showed that the Au–CO band area (major species: metallic gold) varied with preparation method and could be correlated with the observed activity of the catalysts under the WGS feed.

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► The detailed preparation methods of active low temperature gold based water gas shift catalysts based on gold have been found to be critical in determining the activity and stability.
► The drying procedure was found to be particularly important as was the choice of gold precursor.
► Maximum activity was observed for equimolar Ce:Zr ratios in the mixed oxide support.
► Unlike in the case of zirconia supported materials, sulfation only lead to lower activity and stability of the catalysts.
► Over the range of catalysts prepared, a correlation of their activity with the surface concentration of adsorbed CO on the gold was observed showing that this may be used as a measure of the relative number of available active sites for the water gas shift reaction.