Self-Protection Mechanism of Hexagonal WO3-Based DeNOxCatalysts against Alkali Poisoning.
A good catalyst for efficiently controlling NOxemissions often demands strong resistance against alkali poisoning. Although the traditional ion-exchange model, based on acid-base reactions of alkalis with Brønsted acid sites, has been established over the past two decades, it is difficult to be used as a guideline to develop such an alkali-resistant catalyst. Here we establish a self-protection mechanism of deNOxcatalysts against alkali poisoning by systematically studying the intrinsic nature of alkali resistance of V2O5/HWO (HWO = hexagonal WO3) that shows excellent resistance to alkali poisoning in selective catalytic reduction of NOxwith NH3(SCR). Synchrotron X-ray diffraction and absorption spectroscopies demonstrate that V2O5/HWO has spatially separated catalytically active sites (CASs) and alkali-trapping sites (ATSs). During the SCR process, ATSs spontaneously trap alkali ions such as K+, even if alkali ions initially block CASs, thus releasing CASs to realize the self-protection against alkali poisoning. X-ray photoelectron spectra coupled with theoretical calculations indicate that the electronic interaction between the alkali ions and ATSs with an energy saving is the driving force of the self-protection. This work provides a strategy to design alkali-resistant deNOxcatalysts.
Institute of Atmospheric Sciences, Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University , Shanghai 200433, China.
Li
L
Zheng
Institute of Atmospheric Sciences, Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University , Shanghai 200433, China.
Meijuan
M
Zhou
Institute of Atmospheric Sciences, Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University , Shanghai 200433, China.
Zhiwei
Z
Huang
Institute of Atmospheric Sciences, Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University , Shanghai 200433, China.
Yaxin
Y
Chen
Institute of Atmospheric Sciences, Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University , Shanghai 200433, China.
Jiayi
J
Gao
Institute of Atmospheric Sciences, Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University , Shanghai 200433, China.
Zhen
Z
Ma
Institute of Atmospheric Sciences, Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University , Shanghai 200433, China.
Jianmin
J
Chen
Institute of Atmospheric Sciences, Shanghai Key Laboratory of Atmospheric Particle Pollution & Prevention (LAP3), Department of Environmental Science & Engineering, Fudan University , Shanghai 200433, China.|Jiangsu Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CICAEET), Nanjing University of Information Science & Technology , Nanjing 210044, China.
Xingfu
X
Tang
D000468:Alkalies / Q000737:chemistry; D002384:Catalysis; D007477:Ions; D014961:X-Ray Diffraction
D000468:Alkalies; D007477:Ions