Synthesis of novel MnO x @TiO 2 core-shell nanorod catalyst for low-temperature NH 3 -selective catalytic reduction of NO x with enhanced SO 2 tolerance

2018 
Abstract In this study, a MnO x @TiO 2 core-shell catalyst prepared by a two-step method was used for the low-temperature selective catalytic reduction of NO x with NH 3 . The catalyst exhibits high activity, high stability, and excellent N 2 selectivity. Furthermore, it displays better SO 2 and H 2 O tolerance than its MnO x , TiO 2 , and MnO x /TiO 2 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, NH 3 temperature-programmed desorption and H 2 temperature-programmed reduction analyses. The optimized MnO x @TiO 2 catalyst exhibits an obvious core-shell structure, where the TiO 2 shell is evenly distributed over the MnO x 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 4+ active centers after SO 2 poisoning is significantly lower in MnO x @TiO 2 than in MnO x /TiO 2 . The core-shell structure is hence able to protect the catalytic active sites from H 2 O and SO 2 poisoning.
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