Abstract
NO oxidation was conducted over MnOx-CeO2 catalysts, which were synthesized by the co-precipitation method. The calcination temperature and third metal doping were the main considerations. MnCe catalysts calcined at 350 °C and 450 °C attained the highest NO conversion efficiency, compared to 550 °C. XRD results suggested that the higher the calcination temperature, the higher the crystallization degree, which led to a negative effect on catalytic activity. Subsequently, Sn, Fe, Co, Cr, and Cu were separately doped into MnCe composites, but no improvement was observed for these trimetallic catalysts in NO conversion. Nevertheless, MnCeSn, MnCeFe, and MnCeCo still exhibited a desirable NO conversion efficiency, so they were tested under SO2 addition together with MnCe catalyst. Among them, MnCeFe exhibited the highest NO conversion after whole poisoning testing. XPS results indicated that Fe could protect Mn and Ce metal oxides from being reduced during SO2 poisoning process. Furthermore, in in-situ DRIFTS measurement, part of nitrate species maintained undestroyed on the MnCeFe catalyst surface after SO2 poisoning. These characteristics reinforced that Fe dropping would achieve better performance under SO2 atmosphere.
Highlights
BP’s Energy Outlook (2016) predicted that fossil fuels would still maintain the dominant sources of the world energy powering until 2035 [1]
Mn-based, Ce-based, and Zr-based catalysts exhibit excellent performance at low temperature, and their SO2 resistance was enhanced after the modification of other Transition metal oxides (TMO) [4,15,16,17]
MnOx -CeO2 catalysts were synthesized by co-precipitation method to investigate their catalytic activity of NO oxidation
Summary
BP’s Energy Outlook (2016) predicted that fossil fuels would still maintain the dominant sources of the world energy powering until 2035 [1]. Transition metal oxides (TMO) are excellent candidates, given their rich various oxidation states, abundant oxygen defects, and earth rich features [12,13,14] Among these catalysts, Mn-based, Ce-based, and Zr-based catalysts exhibit excellent performance at low temperature, and their SO2 resistance was enhanced after the modification of other TMO [4,15,16,17]. The oxidation atmosphere might have a positive effect on sulfuration [30], while no efficient method to avoid SO2 poisoning exists. A shift in attention to low-sulfur flue gas is a better way to understand the SO2 poisoning process in detail. XRD, XPS, BET and H2 -TPR were used to investigate the catalyst activity, and in-situ DRIFTS measurements were conducted to reveal the NO oxidation and SO2 poisoning process
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