Journal
JOURNAL OF COLLOID AND INTERFACE SCIENCE
Volume 652, Issue -, Pages 923-935Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcis.2023.08.129
Keywords
Selective catalytic reduction; Ce-based catalysts; Fe; Low-temperature; Sulfur resistance
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This study investigates the improvement of low-temperature activity and SO2 durability of ceria-based catalysts by Fe doping. The enhanced low-temperature activity is attributed to the improved redox properties, more active oxygen species, and enhanced adsorption and activation of NOx species. Fe doping also prevents sulfate deposition and alters the competitive adsorption behavior between NO and SO2, leading to excellent sulfur resistance.
Ceria-based catalysts for the selective catalytic reduction of NOx with NH3 (NH3-SCR) are always subject to deactivation by sulfur poisoning. In this study, Fe-doped Ce-W mixed oxides, which were synthesized by the coprecipitation method, improved the SCR activity and SO2 durability at low temperatures of undoped Ce-W oxides. The improved low-temperature activity was mainly due to the enhancement of redox properties at low temperatures and more active oxygen species, together with the adsorption and activation of more abundant NOx species, facilitating the fast SCR reaction. In the presence of SO2, doping with Fe species effectively prevented sulfate deposition on the CeW catalyst, due to the interaction between Fe, Ce, and W species inducing electron transfer among different metal sites and altering the electron distribution. The competitive adsorption behavior between NO and SO2 was changed by Fe doping, in which the adsorption and oxidation of SO2 were restrained. Besides, the elevated NO oxidation accelerated the decomposition of ammonium bisulfate, causing the SCR reaction to not be greatly suppressed. Hence, Fe-doped Ce-W oxides catalysts showed excellent sulfur resistance. This study provides an in-depth understanding of efficient Ce-based catalysts for SO2-tolerance strategies.
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