Catalytic performance of MnO_x-WO₃/TiO₂catalyst for selective catalytic reduction of NO_x with NH₃ and its tolerance towards SO₂

The performance of Mn-W/TiO₂ for selective catalytic reduction(SCR) of NO_x with NH₃ and its resistance to different concentrations of SO₂ at various temperatures were investigated. The results show that WO₃ increased the active sites and enhanced the strength of acid, so it was an effective promoter of MnO_x/TiO₂. The NO_x conversion on Mn-W/TiO₂ ranges from 80.3% to 99.6% between 100 °C to 350 °C at GHSV=18900 h_-1, while N₂ product selectivity changes from 100% to 98.7%. In the presence of 0.01% SO₂ and 6% H₂O, NO_xconversion maintained 98.5% at 120 °C. The influence of more than 0.01% SO₂ on the activity of MnO_x-WO₃/TiO₂ will disappear if the temperature rises above 250 °C. By means of heating and sweeping with He, the activity of the catalysts can be recovered. At 300 °C, NO_x conversion yielded 99% with 0.07% SO₂ and reached the level of commercial V-W/TiO₂ catalysts. The Mn-W/TiO₂ catalyst showed excellent performance for SCR of NO_xwith NH₃ in a wider range of temperature with strong tolerance to SO₂.