title: Investigation of the Poisoning Mechanism of Lead on the CeO2-WO3 Catalyst for the NH3-SCR Reaction via in Situ IR and Raman Spectroscopy Measurement.
abstract: The in situ IR and Raman spectroscopy measurements were conducted to investigate lead poisoning on the CeO2-WO3 catalysts. The deactivation mechanisms were studied with respect to the changes of surface acidity, redox property, nitrate/nitrite adsorption behaviors, and key active sites (note that the results of structure-activity relationship of CeO2-WO3 were based on our previous research). (1) Lewis acid sites originated from CeO2 and crystalline WO3, whereas Brønsted acid sites originated from Ce2(WO4)3. The poisoned catalysts exhibited a lower surface acidity than the fresh catalysts: the number of acid sites decreased, and their thermal stability weakened. (2) The reducibility of catalysts and the amount of active oxygen exhibited a smaller influence after poisoning because lead preferred to bond with surface WOx species rather than CeO2. (3) The quantity of active nitrate species decreased due to the lead coverage on the catalyst and the partial bridged-nitrate species induced by lead exhibited a low degree of activity at 200 °C. (4) Crystalline WO3 and Ce2(WO4)3 originated from the transformation of polytungstate sites. These sites were the key active sites during the SCR process. The formation temperatures of polytungstate on the poisoned catalysts were higher than those on the fresh catalysts.
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University , Beijing 100084, China.|School of Civil and Environmental Engineering and the Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology , 800 West Peachtree Street, Suite 400 F-H, Atlanta, Georgia 30332-0595, United States.
authors.forename: Yue
authors.initials: Y
authors.lastname: Peng
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University , Beijing 100084, China.
authors.forename: Wenzhe
authors.initials: W
authors.lastname: Si
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University , Beijing 100084, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University , Beijing 100084, China.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Chen
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University , Beijing 100084, China.
authors.forename: Junhua
authors.initials: J
authors.lastname: Li
authors.affiliation: School of Civil and Environmental Engineering and the Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology , 800 West Peachtree Street, Suite 400 F-H, Atlanta, Georgia 30332-0595, United States.
authors.forename: John
authors.initials: J
authors.lastname: Crittenden
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University , Beijing 100084, China.
authors.forename: Jiming
authors.initials: J
authors.lastname: Hao
mesh_terms: D000641:Ammonia / Q000737:chemistry; D002384:Catalysis; D002563:Cerium / Q000737:chemistry*; D010084:Oxidation-Reduction; D013059:Spectrum Analysis, Raman
chemical_list: D002563:Cerium; D000641:Ammonia