Heterogeneous Metal Catalysts for Oxidation Reactions

Figure 3

Plausible mechanism for CO oxidation on oxide supported gold catalyst. On the left, a CO molecule is chemisorbed onto a low coordination number gold atom (yellow sphere), and a hydroxyl ion is moved from the oxide support (pink sphere) to an Au (III) ion, creating an anion vacancy. On the right they have reacted to form a carboxylate group, and an oxygen molecule occupies the anion vacancy as O²⁻ (white sphere). This then oxidizes the carboxylate group by abstracting a hydrogen atom, forming carbon dioxide, and the resulting hydroperoxide ion then further oxidizes carboxylate species to form another carbon dioxide, restoring two hydroxyl ions to the support surface, completing the catalytic cycle. (Adapted with permission from Springer) [145].