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

Leaching of CuO by HNO₃ and NH₄OH was carried out to study the nature of active species involved in the oxygen-assisted water-gas shift (OWGS) reaction over a highly active CuPd/CeO₂ catalyst. Since the CO conversion remained above 99% even after removing significant amount of bulk-like CuO, small CuO clusters dispersed on CeO₂ surface and interacting closely with PdO species contributed significantly to the conversion of CO in the OWGS reactions. A significant decrease in the CO conversion over this sample revealed that there is a significant loss in the active species upon NH₄OH treatment. The NH₄OH treatment removed, in addition to the bulk-like CuO, significant amount of highly dispersed CuO that are responsible for the catalytic activity.