The effect of platinum in Cu-Ce-Zr and Cu-Zn-Al mixed oxide catalysts for water–gas shift Original Research Article

Cu-Ce-Zr and Cu-Zn-Al mixed oxide catalysts were prepared by homogeneous co-precipitation with urea. Pt was wet-impregnated on the mixed oxide catalysts. The WGS activity of Cu-Ce-Zr and Cu-Zn-Al mixed oxide catalysts can be related to the Cu reducibility in these catalysts. Low-temperature reducibility correlates with low-temperature activity. Pre-reduction is not absolutely necessary when performing the WGS reaction above the Cu reduction temperature of the catalyst. An adequate reduction procedure may, however, be applied in order to optimize the CO conversion. Pt had no significant effect on the Cu-Ce-Zr mixed oxide catalyst, but altered the properties of the Cu-Zn-Al mixed oxide catalyst. Pt shifted the Cu reduction to lower temperatures, indicating the existence of an interaction between Pt and Cu in the bimetallic catalyst. The effect of Pt on the WGS activity and stability was dependent on the pre-treatment procedure as well as the reaction conditions.