Improvement of low-temperature NH3-SCR catalytic performance over nitrogen-doped MOx–Cr2O3–La2O3/TiO2–N (M = Cu, Fe, Ce) catalysts

A series of MOx–Cr2O3–La2O3/TiO2–N (M = Cu, Fe, Ce) catalysts with nitrogen doping were prepared via the impregnation method. Comparing the low-temperature NH3-SCR activity of the catalysts, CeCrLa/Ti–N (xCeO2–yCr2O3–zLa2O3/TiO2–N) exhibited the best catalytic performance (NO conversion approaching...

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Bibliographic Details
Published in:RSC advances 2021-07, Vol.11 (37), p.22780-22788
Main Authors: Sun, Xiaoyi, Liu, Qingjie, Liu, Shuai, Zhang, Xintang, Liu, Shanshan
Format: Article
Language:English
Subjects:
Adsorption
Ammonia
Anatase
Catalysts
Catalytic activity
Catalytic converters
Cerium
Chemical properties
Chemistry
Chromium oxides
Copper
Doping
Fourier transforms
High temperature
Lanthanum oxides
Low temperature
Nitrogen
Oxygen content
Selective catalytic reduction
Surface chemistry
Titanium dioxide
X ray photoelectron spectroscopy
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Summary:A series of MOx–Cr2O3–La2O3/TiO2–N (M = Cu, Fe, Ce) catalysts with nitrogen doping were prepared via the impregnation method. Comparing the low-temperature NH3-SCR activity of the catalysts, CeCrLa/Ti–N (xCeO2–yCr2O3–zLa2O3/TiO2–N) exhibited the best catalytic performance (NO conversion approaching 100% at 220–460 °C). The physico-chemical properties of the catalysts were characterized by XRD, BET, SEM, XPS, H2-TPR, NH3-TPD and in situ DRIFTS. From the XRD and SEM results, N doping affects the crystalline growth of anatase TiO2 and MOx (M = Cu, Fe, Ce, Cr, La) which were well dispersed over the support. Moreover, the doping of N promotes the increase of the Cr6+/Cr ratio and Ce3+/Ce ratio, and the surface chemical adsorption oxygen content, which suggested the improvement of the redox properties of the catalyst. And the surface acid content of the catalyst increased with the doping of N, which is related to CeCrLa/TiO2–N having the best catalytic activity at high temperature. Therefore, the CeCrLa/TiO2–N catalyst exhibited the best NH3-SCR performance and the redox performance of the catalysts is the main factor affecting their activity. Furthermore, in situ DRIFTS analysis indicates that Lewis-acid sites are the main adsorption sites for ammonia onto CeCrLa/TiO2–N and the catalyst mainly follows the L–H mechanism.
ISSN:2046-2069
DOI:10.1039/d1ra03845a