Synthesis of novel MnOx@TiO2 core-shell nanorod catalyst for low-temperature NH3-selective catalytic reduction of NOx with enhanced SO2 tolerance

In this study, a MnOx@TiO2 core-shell catalyst prepared by a two-step method was used for the low-temperature selective catalytic reduction of NOx with NH3. The catalyst exhibits high activity, high stability, and excellent N-2 selectivity. Furthermore, it displays better SO2 and H2O tolerance than its MnOx TiO2, and MnOx/TiO2 counterparts. The prepared catalyst was characterized systematically by transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Raman, BET, X-ray photoelectron spectroscopy, NH3 temperature-programmed desorption and H-2 temperature-programmed reduction analyses. The optimized MnOx@TiO2 catalyst exhibits an obvious core-shell structure, where the TiO2 shell is evenly distributed over the MnO nanorod core. The catalyst also presents abundant mesopores, Lewis-acid sites, and high redox capability, all of which enhance its catalytic performance. According to the XPS results, the decrease in the number of Mn active centers after SO2 poisoning is significantly lower in MnOx@TiO2 than in MnOx/TiO2. The core-shell structure is hence able to protect the catalytic active sites from H2O and SO2 poisoning. (C) 2018, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.