Catalytic reduction of NOx and oxidation of dichloroethane over a-MnO2 catalysts: Properties-Reactivity relationship

The reduction ability of NO to N2 and the oxidation performance of 1,2-dichloroethane (DCE) over a-MnO2 catalysts were investigated. The results show that a-MnO2-3 exhibited the highest catalytic activity in 63.5 % conversion of NOx reduction by C3H8 at 250 degrees C, and 80 % con-version of DCE combustion by O2 at 338 degrees C. It is revealed the active phase of a-MnO2-3 is tetrag-onal a-MnO2 with the selectively exposed plane of (211). It was proposed the high DCE decomposition of a-MnO2-3 was ascribed to the redox properties. The overall characterization results revealed that a-MnO2-3 catalyst preserves more active sites of low valence Mn and higher surface adsorbed oxygen (Oads) /lattice oxygen (Olatt) at the outermost layers, and lower reduction temperature in H2-TPR profiles than that of other catalysts. Meanwhile, NH3-TPD profile of a-MnO2-3 also shows a large number of acid sites promote NOx reduction.(c) 2023 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

The reduction ability of NO by γ-MnO2 catalysts and the oxidation performance of 1,2-dichloroethane were investigated. The results showed that γ-MnO2-3 exhibited the highest catalytic activity with 63.5% conversion of NOx at 250°C and 80% conversion of DCE at 338°C. The active phase of γ-MnO2-3 was tetragonal γ-MnO2 with the selectively exposed plane of (211), and it had more low valence Mn active sites, higher surface adsorbed oxygen (Oads) /lattice oxygen (Olatt) ratio, and lower reduction temperature in H2-TPR profiles compared to other catalysts.