Room temperature CO oxidation over AgCuO₂

Mixed silver–copper oxide AgCuO₂ is able to interact with CO at room temperature (RT). Such interaction is provided by the participation of the reactive oxygen species associated with deeply oxidized states of silver Ag^(1+δ)+ and copper Cu^(3-δ)+. CO conversion increases by more than about 20% when O₂ appears in the reaction mixture. It indicates the contribution of catalytic oxidation over AgCuO₂ with participation of gas–phase oxygen. It was shown that oxidizing ability of AgCuO₂ decreased during prolonged interaction as a result of accumulation of surface bicarbonates. The rate of AgCuO₂ deactivation at RT is significantly increased under wet conditions. The examination of thermal stability under reducing reaction medium showed that the AgCuO₂ crystal structure is not stable at temperatures higher than 75 °C. Above this temperature, sequential decomposition takes place with the formation of Ag₂Cu₂O₃ and, then, a mixture of Ag⁰ and CuO. Such transformation results in the loss of oxidizing ability at RT.