Catalytic performance and SO 2 tolerance of tetragonal-zirconia-based catalysts for low-temperature selective catalytic
- PDF / 562,493 Bytes
- 8 Pages / 584.957 x 782.986 pts Page_size
- 35 Downloads / 220 Views
Feng Jia School of Environment, Nanjing Normal University, Nanjing, China; and Nanoparticle and Air Quality Laboratory, Institute of Environmental Engineering, National Chiao Tung University, Taiwan, China (Received 12 April 2016; accepted 14 July 2016)
MnOx–CeO2/t-ZrO2 catalyst was prepared by impregnation of nanotetragonal zirconia. The NO conversion of 5 wt% MnOx–CeO2/t-ZrO2 catalyst was 68.1% at 100 °C while that of 30 wt% MnOx–CeO2/t-ZrO2 catalyst was 97.4%. The x-ray diffraction, Brunner–Emmet–Teller measurements (BET), and H2-TPR showed surface properties of the prepared catalysts were good for selective catalytic reduction reactions. X-ray photoelectron spectroscopy analysis indicated that Mn41 and Ce41 oxidation states were predominant on the surface of the catalyst and so was lattice oxygen which was conducive to Lewis acid sites. NH3-TPD test results demonstrated that Lewis acid sites are predominant on the surface of catalyst. The presence of SO2 reduced the catalyst activity. The realized conversion dramatically decreased to 47% from nearly 100% after 8 h. Characterization of fresh and spent catalysts indicated the deterioration of active component and deposition of NH4HSO4 or (NH4)2SO4 contribute to SO2 poisoning. I. INTRODUCTION
NOx is potentially harmful to humans as a kind of primary pollutant. And NOx are the main cause of many environment problems, such as acid rain, surface ozone pollution, and particulate matter 2.5.1 The emission of NOx was 2337.8 tons in China in 2011 and 2275.4 tons in 2012.2 Emission standard of air pollutants for thermal power plants which came into effect on January 1, 2012 requires the emission concentration of NOx under 100 mg/m3. Selective catalytic reduction (SCR) of NOx with NH3 is the most promising method to remove NOx. Catalysts with high activity play a decisive part in low-temperature SCR technology. Many researches about metal oxide as SCR catalyst support have been reported recently, such as TiO2,3 Al2O3,4 activated carbon5,6 and molecular sieve.7 Zirconium oxide has attracted considerable attention recently as a catalyst support because of its special characteristics. Cao et al.8 found that incorporating the Zr41 ions into the CeO2 crystal could form solid solution, and increase the BET surface area and poresit, comparing with Mn–Ce catalyst. Yan et al.9 reported that the existence of ZrO2 in catalysts can enhance the dispersion of CeO2 on catalysts which results in high activity of the Contributing Editor: Gary L. Messing a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.283
catalysts. Takahashi et al.10 investigated the influence of various compositions of TiO2 and ZrO2 on NOx removal over a sulfur-treated NOx storage and reduction (NSR) catalyst and found that TiO2–ZrO2-supported metal oxide catalysts have the best catalytic activity. Reddy et al.11 investigated structural characteristics of nano-sized ceria– silica, ceria–titania, and ceria–zirconia mixed oxide catalysts and found that these mixed oxides exhib
Data Loading...
