Study on NH3-SCR denitrification and sulfur poisoning resistance performances of SSZ-13 molecular sieve supported MnCeOx catalysts
In order to improve the low-temperature SCR denitrification and SO2 poisoning resistance performances of MnCe-based oxides,MnCeOx/SSZ-13 catalysts are prepared through loading metal oxides on molecular sieves,and the impacts of MnCeOx loading amount and silica-aluminum ratio of molecular sieve on the denitrification activity and sulfur resistance performances are explored.Results show that the catalyst exhibits the best denitrification performance when the feeding ratio of MnCeOx to SSZ-13 is 20%,delivering a NO conversion greater than 90%in the range of 180-400℃and a N2 selectivity of 100%in the range of 100-250℃.NO conversion can maintain at around 80%after passing 100 μL·L-1 SO2 at 200℃.Higher MnCeOx loading amount helps to enhance NO conversion,but leads to a slight decline of N2 selectivity.NO conversion,N2 selectivity and the sulfur poisoning resistance of the catalysts all decrease with the prolongation of the pickling time,the increase of the concentration of the acid solution,and the decrease of the silica-aluminum ratio of SSZ-13.MnCeOx provides surface-active oxygen species to activate NO and O2 at low temperature to improve the catalysts'low-temperature SCR activity,and SSZ-13 molecular sieve provides acidic sites to adsorb NH3,while the domain-limiting effect of the molecular sieve helps to improve the catalyst's resistance to SO2 poisoning.
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