Leaching studies of a highly active Cu-Pd bimetallic catalyst supported on nanostructured CeO₂ for oxygen-assisted water-gas shift reaction

A new series of Cu-Pd bimetallic catalysts containing various amounts of Cu and Pd supposed on a high surface area CeO₂ obtained by urea gelation method was developed for the oxgen-assisted water-gas shift reaction. The catalysts that contained 30 wt % Cu and 1 wt % Pd exhibited the best performance with a CO conversion exceeding 99 % around 210°C under extremely high (∼ 84%) H₂ atmosphere. Scanning electron microscopic studies of the catalyst showed the existence of Cu-rich and CeO₂-rich regions. The sample treated with HNO₃ for 15 hr retained the original catalytic activity of over 99% CO conversion. On the other hand, the CO conversion dropped to ∼ 69% over the sample treated with NH₄OH for the same period of time. TPR of the HNO₃ treated sample exhibited a sharp reduction peak around 130°C compared to a broad peak centering around 160°C observed for the unleached sample. Small CuO clusters dispersed on CeO₂ and interacting closely with PdO contributed significantly to the CO OWGS reaction. The nature of active species involved in the reaction was further investigated by XRD, XPS, and SEM characterizations of the leached as well as unleached samples. This is an abstract of a paper presented at the 228th ACS National Meeting (Philadelphia, PA, 8/22-26/2004).