Synthesis Of Porous Manganese Oxide

This paper focused on the optimization of OL and porous structure OMS synthesis processes and XRD, BET and Micro-Reactor-Chromatography were used to study effect of preparation factors on OL and OMS manganese oxides.For the manganese oxides of OL structure, the OL-1 phase was not the only phase detected in the samples and the Feitknechtite phase was also contained. when the synthesis temperature is higher than 45℃the temperature is not the main influence factor to prepare OL-1. The crystalline of Feitknechtite improve with Mn²⁺/MnO4- increasing and the best value in preparing the OL-1 manganese oxide is Mn²⁺/MnO4-=70.8/29.2. It is showed that KOH as the precipitator is not suitable to the formation of OL-1 structure and the specific surface area of samples. It is proved that manganese acetate as the source of Mn is better than manganese sulfate. The Feitknechtite phase disappeared when the Cu²⁺ was added in the solution. Purely OL-1 manganese oxide can be synthesized through oxidation style. The results showed that the flux of O2 is the pivotal factor for the synthesis of OL-1 manganese oxide. Only the solution with high oxygen content has enough oxygen diffusion force for formation of purely OL-1. Hausmanite is the main phase when the oxidation time is lesser than 3h, and pure OL-1 structure can be detected when it is more than 5h. Manganese nitrate as the starting material of Mn is better than manganese sulfate. The effect of H2O2 treatment after the layer manganese oxide is formatted is very small.Buserite synthesized by oxygen can not transformed into porous manganese oxide structure under the acidic reaction condition, H2O and alkaline, but under alkaline medium the crystallization of OL-1 is further optimized. Buserite transformed into OMS-1 structure after ion-exchanged with Cu ion, but buserite maintained after ion-exchanged with Mg and Ca ions. OMS-1 can be synthesized by oxygen when the Mg ion was added in the original solution.