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 KMnO4, and the ordered mesostructure has been kept with large surface area.