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摘要
The impact of sulphur and hydrothermal aging on W-CeZr and CeZr catalysts was investigated. Sulphur treatments for W-CeZr and CeZr were done in the absence and presence of water (S- and S + H2O-treatments, respectively) for 5 h at 400 degrees C. Similarly, hydrothermal aging (H2O-treatment) for W-CeZr and CeZr catalysts was done in a gas phase. The W and S contents were analyzed using XRF. The studied catalysts were characterized by BET, BJH, DRIFTS, XPS and NH3 desorption methods. In addition, the activity of the catalysts was tested in NH3-SCR reaction. The NOx conversion over the fresh W-CeZr catalyst was 85 % at 350 degrees C whereas the fresh CeZr was not active in NOx reduction. In the case of W-CeZr and CeZr catalysts, S + H2O and S-treatments increased the NOx conversion up to 92-98 % at the temperature range of 350-400 degrees C. The increased portion of chemisorbed oxygen due to S- and S + H2O-treatments enhances the NOx reduction reactions. The water treatment had no effect on the NH3-SCR activity which indicates that the S-compounds are the major reason for enhanced activity.
- 出版日期2015-10
