Effect Of Sb_xO_y On Mn/PG Catalyst Resisted To SO₂ Poisoning For Selective Catalytic Reduction Of NO By NH₃ At Low Temperatures

Selective catalytic reduction (SCR) has been demonstrated as a feasible technology to reduce NOx emission from stationary sources. Recently, Low-temperature SCR Technology has attracted more and more attentions for its low energy consumption and operating cost. Based on there view of the current situation of SCR technology, it was pointed out that the following shortcomings are the main obstacle of the industrial application of the low-temperature SCR technology:low activity at low temperature, poor SO2 resistance of catalysts and uncertainty of reaction and SO2-poisoning mechanisms. In order to solve these problems, the low-temperature SCR reaction was thoroughly investigated for Mn-based catalysts in this dissertation.Firstly, several metals were chosen to be doped into Mn/PG catalyst. Based on the results of activity tests and characterization results, it was found that Sb doping could greatly enhance the low-temperature SCR activity of the catalyst (the activity was enhanced from 38% to 98% at 150 ?). The addition of Sb oxides led Mn oxides to highly disperse on the catalyst's surface. Besides, the surface acidity of the Mn/PG catalyst were improved by introduction of Sb, which would be beneficial to the adsorption of NH3 and its activation.Furthermore, the effect of SO2 on the SCR activity of Mn/PG and MnSbx/PG catalysts as well as its mechanism was also investigated systematically. A serious of deactivation by SO2 was detected on Mn/PG catalyst. The sulfation of catalyst active phase (MnOx) was proved to be the main reason for the catalyst deactivation in the presence of SO2 during SCR reaction. Sb doping could effectively inhibit the sulfation of catalyst active phase (MnOx) and MnOx as the sole active phase could be stable existed and continued to participate in the SCR reaction.Finally, the physical and chemical properties of non-supported catalysts were investigated. The intrinsic relationship between physicochemical properties of manganese based catalyst prepared in different methods and SCR performance resisted to SO2- poisoning were discussed.