Facile synthesis of synthetic todorokite (OMS-1), co-precipitation reactions in the presence of a microwave field

A new application of microwave heating, co-precipitation in the presence of a microwave field, has been investigated. We report herein the synthesis of the octahedral molecular sieve, OMS-1 (synthetic todorokite), a manganese oxide that also contains magnesium, sodium, and/or other cations. Microwave aging of OMS-1 has been used to produce a pure phase material with increased catalytic activity. The material synthesized here shows no extraneous peaks in its XRD pattern, and can be synthesized in less than 20 h by microwave heating, as compared to 3-7 days by conventional heating. The material has been characterized using X-ray powder diffraction (XRD), infrared spectroscopy (FTIR), thermal analysis, surface area, scanning electron microscopy (SEM), Auger, and elemental analyses. The materials prepared via microwave methods were compared to materials synthesized under similar conditions but by using conventional heating. Differences in these two sets of samples were noted via FTIR, SEM, surface area, extent of crystallinity, time of the total processing and catalytic activity experiments. This paper focuses on the synthetic parameters that control properties of resultant materials, which can lead to a better understanding of why microwave heating produces more crystalline products than conventional healing. (C) 1998 Elsevier Science B.V.