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Bi-jun WUa, b, , , Xiao-qin LIUa, Ping XIAOb and Shu-gang WANGa
aChemical Engineering Institute, Nanjing University of Technology, Nanjing 210009, P. R. China
bState Power Environmental Protection Research Institute of China Guodian Corporation, Nanjing 210031, P. R. China
Available online 27 November 2008.
Abstract
Binary metal oxide(MnOx-A/TiO2) catalysts were prepared by adding the second metal to manganese oxides supported on titanium dioxide(TiO2), where, A indicates Fe2O3, WO3, MoO3, and Cr2O3. Their catalytic activity, N2 selectivity, and SO2 poisonous tolerance were investigated. The catalytic performance at low temperatures decreased in the following order: Mn-W/TiO2>Mn-Fe/TiO2>Mn-Cr/TiO2>Mn-Mo/TiO2, whereas the N2 selectivity decreased in the order: Mn-Fe/TiO2>Mn-W/TiO2>Mn-Mo/TiO2>Mn-Cr/TiO2. In the presence of 0.01% SO2 and 6% H2O, the NOx conversions in the presence of Mn-W/TiO2, Mn-Fe/TiO2, or Mn-Mo/TiO2 maintain 98.5%, 95.8% and 94.2%, respectively, after 8 h at 120 °C at GHSV 12600 h-1. As effective promoters, WO3 and Fe2O3 can increase N2 selectivity and the resistance to SO2 of MnOx/TiO2 significantly. The Fourier transform infrared(FTIR) spectra of NH3 over WO3 show the presence of Lewis acid sites. The results suggest that WO3 is the best promoter of MnOx/TiO2, and Mn-W/TiO2 is one of the most active catalysts for the low temperature selective catalytic reduction of NO with NH3.
Keywords: Selective catalytic reduction of NO with NH3; Low-temperature selective catalytic reduction; Binary metal oxide catalyst; FTIR; NH3-TPD