Manganese Oxides Supported on TiO₂–Graphene Nanocomposite Catalysts for Selective Catalytic Reduction of NO_<i>X</i> with NH₃ at Low Temperature

Abstract

TiO2–graphene (TiO2–GE) nanocomposites were prepared by the sol–gel method with different mass ratios of graphene (0–2% wt %). With the MnOX active component loaded by means of ultrasonic impregnation, the catalysts exhibited excellent structure and electrical properties, which favored the catalytic reaction. All the catalysts were characterized by XRD, SEM, TEM, BET, FT-IR, XPS, and Raman spectroscopy. The results indicated that the reduction of graphene oxide and formation of graphene in TiO2–GE supports and TiO2–graphene were readily indexed to anatase TiO2 in all samples. Various valences of manganese species coexisted in MnOX/TiO2–GE catalysts. Especially, nonstoichiometric MnOX/Mn on the surface of composite catalyst was beneficial to the electron transfer; therefore, the redox performance of the catalyst was improved. The MnOX/TiO2–0.8%GE catalyst exhibited good resistance to simultaneous H2O and SO2, as well as to only H2O, with an optimum Mn mass ratio of 7 wt %. All the samples showed excellent N2 selectivity.