Journal
APPLIED CATALYSIS B-ENVIRONMENTAL
Volume 232, Issue -, Pages 246-259Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.apcatb.2018.03.065
Keywords
CeO2 morphology; Sulfation; Solid acid; Ammonia adsorption; In situ DRIFTS
Funding
- National Key Research and Development Program of China [2017YFC0210701, 2017YFC0211102]
- National Natural Science Foundation of China [51478241]
- international postdoctoral exchange fellowship program [20140054]
Ask authors/readers for more resources
Thermally stable CeO2 cubes and nanospheres were synthesized and modified by sulfation treatment. Non-sulfated CeO2 cubes and nanospheres did not exhibit good catalytic performance for selective catalytic reduction of NOx with NH3 (NH3-SCR), but mainly contributed towards an undesired side reaction of NH3 oxidation above 350 degrees C. Based on the structural, morphological and physicochemical characterization, it was observed that CeO2 nanospheres comprising small crystallites could easily release active oxygen species, which resulted in strong NH3 oxidation. However, sulfation treatment greatly improved the catalytic performance of NH3-SCR on both CeO2 cubes and nanospheres. Sulfated CeO2 catalysts did not contribute to significant NH3 oxidation due to the inhibited reducibility of Ce4+ coordinated with the surface sulfates. The adsorbed ammonia could be activated on Bronsted acid sites generated by the formation of surface Ce-2(SO4)(3) species, while gaseous NOx could be activated on separate surface sites of Ce4+. The presence of separate reaction sites for NH3 and NOx is believed to be important for the improved catalytic performance of SCR reaction. Sulfated CeO2 cubes outperformed sulfated CeO2 nanospheres in the entire test temperature window (200-500 degrees C). The improved performance of sulfated CeO2 cubes appears to be related to surfaces with abundant Bronsted acid sites and relatively weak reducibility of Ce4+. These fundamental findings contribute to a better mechanistic understanding needed for designing efficient CeO2-based NOx reduction catalysts in the future.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available