Active Coordinatively Unsaturated Manganese Monoxide-Containing Mesoporous Carbon Catalyst in Wet Peroxide Oxidation

Abstract

A novel heterogeneous coordinatively unsaturated manganese monoxide-containing mesoporous carbon catalyst (C-MnO) is reported here. The catalysts exhibit high catalytic activity in wet oxidation of phenol (almost complete mineralization with an initial concentration of 50 mg/L at atmospheric pressure) and stability (reused 20 times without obvious activity loss or metal leaching), and they take more advantages than most developed heterogeneous Fenton catalysts. The one-pot surfactant self-assembly approach is used for the synthesis of the mesoporous C-MnO catalysts. Small-angle X-ray diffraction (XRD), N-2 sorption, and transmission electron microscopy results reveal that the catalysts have the ordered two-dimensional hexagonal mesostructure, large surface areas (530-552 m(2)/g), uniform pore sizes (3.3-5.4 nm), and large pore volumes (0.34-0.44 cm(3)/g); MnO nanoparticles (<12 nm) are well dispersed inside carbon mesopore systems with high crystallinity. The wide-angle XRD pattern reveals the presence of cubic rock salt structure MnO, and the Mn K-edge X-ray absorption fine structure spectra confirms the low chemical valence and the coordination unsaturated state of Mn. The high activity and stability of C-MnO catalysts might be related to the mesostructure, carbon pore wall, and, more importantly, the confined undercoordinative MnO nanoparticles.