An investigation on the structure and catalytic activity of cryptomelane-type manganese oxide materials prepared by different synthesis routes

Abstract

Cryptomelane is an octahedral molecular sieve with a 2 × 2 tunnel structure (OMS-2) and a stoichiometric formula of approximately KMn8O16. Cryptomelane OMS-2 is gaining increasing attention in a range of applications, including catalysis. However, the impacts of synthesis methods on catalytic performance are still not well understood. Cryptomelane OMS-2 was prepared in this study by three methods: (1) a sol–gel method, (2) a reflux method, and (3) a milling method. The physical and chemical characteristics of these materials were investigated, and the catalytic performances of these materials were compared for the gas phase oxidation of ethanol. A novel aspect of this study is that cryptomelane was prepared by the milling method using post-consumer alkaline battery waste, and this novel cryptomelane material was compared with others prepared from commercially-available precursors and published laboratory methods.