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Abstract:
Different crystallographic structures of Mn oxides usually lead to diverse coordination geometries and oxidation states of MnO6, which in turn show strikingly different catalytic activities. In this study, methane oxidation performances over Mn oxides with various crystalline structures were investigated, including α-MnO2 (double chains of Mn4+O6 octahedra), α-Mn2O3 (symmetry-inequivalent Mn3+O6), two-dimensional mesoporous β-MnO2 (labels as Meso-MnO2, single chains of Mn4+O6 octahedra) and one-dimensional β-MnO2 (single chains of Mn3+/4+O6 octahedra). The results demonstrate that the methane oxidation activities are dependent on their crystallographic structures, and follow an order of α-MnO2 > β-MnO2> α-Mn2O3 > Meso-MnO2. Meanwhile, α-MnO2 exhibits good durability and excellent 9.5vol%H2O/10vol%CO2 resistance ability. EXAFS, Raman, XPS, O2-TPD-MS and CH4-TPR-MS studies indicate that the outstanding catalytic activity over α-MnO2 is due to higher surface Mn concentration, more active oxygen species and mono-μ-oxo bridged corner-shared [MnO6] sites, and excellent reducibility. More importantly, a new insight into reaction mechanism of methane oxidation over Mn oxides was proposed at the molecular level. © 2018 Elsevier B.V.
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Applied Catalysis B: Environmental
ISSN: 0926-3373
Year: 2018
Volume: 229
Page: 52-62
1 4 . 2 2 9
JCR@2018
2 0 . 3 0 0
JCR@2023
ESI HC Threshold:209
JCR Journal Grade:1
CAS Journal Grade:1
Cited Count:
SCOPUS Cited Count: 65
ESI Highly Cited Papers on the List: 0 Unfold All
WanFang Cited Count:
Chinese Cited Count:
30 Days PV: 1
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