Abstract
The sulfur resistance in NH3-SCO and NH3-SCR reactions of 1%Cu/SCR catalyst prepared by improved wet impregnation method was tested at 350 °C. In the presence of 500 ppm SO2, 1%Cu/SCR maintained good SCR performance, but its NH3 oxidation efficiency was visibly decreased. The NH3 conversion was promoted to about 90% after adding NO since SCR reactions occurred. As observed in ionic chromatography spectra, no more SO3 were generated over the Cu doped catalyst. NH3-TPD, H2-TPR results showed that some sulfite and sulfate species on the catalyst surface significantly increased the amount of weak acid sites and decreased the reducibility of copper species. In addition, the influence mechanism of SO2 on NH3 and NO adsorption and conversion over 1%Cu/SCR catalyst were revealed by using in situ DRIFT methods. The suppression of NH2 → NOx conversion could account for the SO2 deactivation in NH3 oxidation. Gaseous NO can directly react with NH2 through iSCR mechanism.
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