Effects of Microwave Processing on Chemical, Physical, and Catalytic Properties of Todorokite-Type Manganese Oxide

A microwave-assisted hydrothermal method of synthesis was used to prepare todorokite. Synthetic todorokite, OMS-1, is a multivalent manganese oxide with a 3×3× tunnel structure. OMS-1 was synthesized from its layered precursor much faster by the microwave method than by conventional heating (8 vs 48 h). In addition, the microwave-synthesized materials reveal some properties superior to those of the conventionally synthesized ones such as better stability, crystallinity, and catalytic activity in the production of phthalic anhydride. Microwave-prepared todorokite also shows novel cubic morphology, which was not found for conventionally made OMS-1 and is catalytically active in the oxidation of benzyl alcohol. Materials synthesized by microwave as well as conventional methods were characterized with XRD, TGA, SEM, TEM, TPD, and BET. Physical, chemical, and catalytic properties of todorokite prepared by the two different methods were compared based on the experimental results