Characterization and performance of common alkali metals and alkaline earth metals loaded Mn/TiO2 catalysts for NOx removal with NH3. Issue 2 (April 2019)

• Record Type: Journal Article
• Authors: Fang, De; He, Feng; Xie, Junlin
• Is Part Of: Journal of the Energy Institute. Volume 92:Issue 2(2019)
• Page Start: 319
• Page End: 331
• Publication Date: 2019-04
• Subjects: Alkali metals -- Alkaline earth metals -- Mn/TiO2 -- NH3-SCR -- NO removal; Power (Mechanics) -- Periodicals; Power resources -- Periodicals; Fuel -- Periodicals; 621.04205
• DOI: 10.1016/j.joei.2018.01.004
• Languages: English
• ISSNs: 1743-9671

Abstract

Abstract: The influence of four common alkali metals and alkaline earth metals (Na, K, Mg and Ca) on Mn/TiO2 catalysts for selective catalytic reduction of NOx with NH3 was investigated. K, Na and Ca deactivated the catalysts and the deactivation effects were shown in sequence as K > Na > Ca, while Mg improved the capability of the catalysts. Furthermore, physical and chemical properties of catalysts were characterized by XRD, H2 -TPR, NH3 -TPD, BET, FESEM, XPS, TG and in situ DRIFTS analyses. Characterization results suggested that the obvious decrease of NH3 adsorption and surface redox ability and the formation of inactive compounds could take credit for the deactivation caused by alkali metals and alkaline earth metals except Mg. The atomic concentrations of Mn 3+ and relative concentration ratios of Oα /(Oα +Oβ ) on the surfaces were also important factors for SCR activities of Mn/TiO2 catalysts doped with the main group IA elements (Na and K). The in situ DRIFTS tests further confirmed that the alkaline size resulted in the considerable changes in the desorption strength of ammonia which was in accordance with the NH3 -TPD results. Meanwhile, the slight decrease of NH3 adsorption and surface redox ability and the formation of MgMn2 O4 appeared to be directly correlated with the better SCR performance of the catalysts doped with Mg. Moreover, acid site and redox site played important roles in the catalytic cycle for Mn/TiO2 catalysts during the NH3 -SCR reaction. Graphical abstract: K, Na and Ca deactivated the catalysts and the deactivation effects were shown in sequence as K > Na > Ca, while Mg improved the capability of the catalysts. Highlights: K, Na and Ca deactivated catalysts in sequence as K > Na > Ca. K, Na, Ca and Mg changed adsorption and redox ability and active ingredients. Catalytic properties of MgMn2 O4 might induce enhancement of NOx removal. Oα /(Oα +Oβ ) ratios, acid site and redox site affected catalytic cycle of NH3 -SCR.