CHAPTER 13: Porous Cryptomelane-type Manganese Oxide Octahedral Molecular Sieves (OMS-2); Synthesis, Characterization and Applications in Catalysis

This chapter is an overview of cryptomelane-type manganese octahedral molecular sieves (OMS-2). Manganese oxide octahedral molecular sieves (OMS) are an unique class of materials. One key phase showed excellent catalytic, electrochemical and adsorption properties, due to high porosity, mixed valency, and semiconductivity. The phase is a synthetic cryptomelane phase, or, according to the OMS nomenclature, it is called OMS-2. This material has applications in a vast range of areas such as sensors, fuel cells, separation, energy storage, battery materials, environmental remediation, and as a catalyst material. The primary focus of this summary will be on the structural properties, characterization, different synthetic routes using different energy sources, various precursor selection, control of morphology, porosity, particle size and the effect of these factors on the catalytic activity of the OMS-2 phase. A variety of different catalytic reactions catalyzed by OMS-2 will also be discussed, including gas and liquid phase catalytic reactions.