| The selective catalytic reduction with NH3 as reductant ?NH3-SCR? is the most widely applied NOx removal techniques. NH3-SCR can selectively reduce NOx to N2 and H2O, and therefor dimish the NOx from the flue gas.The CeO2 was well studied by doping of other metal to improve the performance in this thesis. Six two-metal-oxides Ce-X ?where X is Cr, Zr, Mo, Sn, W, Mn, respectively? and two supported catalysts ?Ce/TiO2 and Ce/C? were prepared. The influence of precipitant, calcination temperature, etc. were studied. The most excellent catalyst are Ce-Mn samples considering the NO converstion and N2 selectivity, and Ce-Sn and Ce-W systems are promising catalysts.Ce-Mn-Sm, Ce-Mn-Sn, Ce-Mn-W and Ce-W-Sn were prepared condering the of two-metal oxides, and results showed that the doping metal could indeed improve the catalytic performance of the catalysts. The Ce0.5Mn0.4Sn0.1 has the best catalytic performance among Ce-Mn-Sn system which is the best among the four three-metal oxides, with >90% NO conversion at 100?300??W was doped to improve the N2 selectivity, which decreased the formation of N2O and improved the NOx converstion. The Ce-Mn-Sn-W0.3 sample showed about 80% NOx converstion and higher N2 selectivity than Ce-Mn-Sn sample. The results of H2-TPR indicated that W could adjust the redox acitivity of the catalyst, and in situ DRIFTS approved that doping of W could improve the acidity of the catalysts. Besides, Ce-Mn-Sn-W showed good H2O and SO2 resistance. |
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