Silver-manganese mixed oxide with crednerite structure as a catalyst for low-temperature catalytic CO oxidation

Abstract

The paper describes the conditions for the preparation of AgMnO2 particles with the crednerite structure without impurity crystallized phases. It was shown that catalytic properties of AgMnO2 in CO oxidation might be different in dependence on the nature of the alkali-containing precursor used. The highest catalytic activity was achieved when using a combination of K- and Na-containing precursors. It has been found that the low-temperature catalytic activity of AgMnO2 increases noticeably with a decrease in the relative silver amount. An in situ X-ray diffraction study revealed a partial release of silver from crednerite structure with the formation of Ag0 particles when AgMnO2 was heated in a CO+O2 mixture to 150–200 °C, whereas heating to 250 °C followed by cooling to room temperature led to the incorporation of silver back into crednerite structure. The low-temperature catalytic activity of AgMnO2 correlates with the amount of weakly bounded oxygen species on the surface.