Effects of Inorganic Cation Templates on Octahedral Molecular Sieves of Manganese Oxide

Five hydrated inorganic divalent cations, Mg[sup 2+], Co[sup 2+], Ni[sup 2+], Cu[sup 2+], and Zn[sup 2+], have successfully been used as templates for the synthesis of manganese oxide octahedral molecular sieves (OMS-1) having the todorokite structure. The OMS-1 samples have been well characterized by X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy/energy dispersive X-ray studies, inductively coupled plasma analysis, electron paramagnetic resonance, Fourier transform infrared spectroscopy, thiosulfate titration, and cyclohexane sorption. Catalytic CO oxidation and 2-propanol decomposition were carried out. Results show that these OMS-1 samples with a tunnel size of about 6.9 angstroms are crystalline and chemically pure. They have the following formulas: Mg[sub 3.17]Mn[sub 5.05]O[sub 12] [center dot] 4.52H[sub 2]O, Co[sub 1.84]Mn[sub 5.59]O[sub 12] [center dot] 3.45H[sub 2]O, Ni[sub 1.64]Mn[sub 5.75]O[sub 12] [center dot] 4.19H[sub 2]O, Cu[sub 3.50]Mn[sub 4.45]O[sub 12] [center dot] 5.33H[sub 2]O, and Zn[sub 3.55]Mn[sub 4.47]O[sub 12] [center dot] 2.59H[sub 2]O. Their thermal stability largely depends on the nature of the cations. 47 refs., 16 figs., 3 tabs.