Investigation on Mn-loaded mesoporous silica MCM-41 prepared via reducing KMnO₄ with in situ surfactant

A series of manganese-loaded mesoporous materials MCM-41 (MnMCM-x, x = 0.005, 0.01, 0.05, and 0.1) were synthesized by a facile in situ reduction method with potassium permanganate (KMnO₄) and the surfactant template. It was found from the results of Fourier transform infrared spectroscopy that, as the concentration of KMnO₄ solution increased, the amount of remaining surfactant template in the pore channels decreased and meanwhile the content of loaded manganese increased. KMnO₄ was found to be reduced to manganese oxides of low charge states of Mn by X-ray photoelectron spectroscopy. These results prove that the permanganate ions were reduced by the surfactant within the pores, rather than ion-exchanged by the D4R (negatively charge silica species) anions. Different contents of manganese species have been introduced by changing the initial concentration of KMnO ₄, and the ordered mesostructure has been kept with large surface area.