Synthesis of Mn2O3 from Manganese Sulfated Leaching Solutions

Abstract

Manganese trioxide (Mn2O3) is one of the most important manganese compounds for the electronic industry. It is widely used for preparing the cathode component in primary and secondary batteries and electronic devices employed for electrocatalysis. There is a lack of information regarding the feasibility of employing a manganese mineral feedstock for the synthesis of Mn2O3. Hence, in the present work, research efforts were devoted to investigating a new processing route to obtain Mn2O3, which involved the leaching of pyrolusite mineral to first obtain a manganese sulfate solution. Subsequently, Mn(OH)2 was produced by adding an alkaline solution of NaOH. The Mn3O4 particles were successfully produced by aging the Mn(OH)2 precursor gel at 25 °C for 24 h in air. Finally, the precursor Mn3O4 was treated with acetic acid solutions resulting in the formation the oxy-hydroxide of manganese (α-MnO(OH)) and manganese acetate (Mn(CH3COO)2). The precipitated solid was then successfully transformed to manganese trioxide (Mn2O3) by thermal decomposition, which was conducted at temperatures between 600 and 700 °C in air.