Preparation and catalytic activity of nickel–manganese oxide catalysts in the reaction of partial oxidation of methane

Highly Efficient Al-Doped Ni–Mn–O Catalysts for Auto-Thermal Reforming of Acetic Acid: Role of MnAl2O4 for Stability of Ni Species

“…42,43 For the NM catalyst presented in Figure 8(1) with phases of Mn 2 O 3 /Mn 3 O 4 /NiMn 2 O 4 , because of the high content of manganese, the reduction peaks of Mn within Mn 2 O 3 and Mn 3 O 4 overlapped and merged into one peak at about 529 °C; meanwhile, the reduction peak at 739 °C can be ascribed to species of lattice nickel (Ni latt ) within NiMn 2 O 4 , which can be considered as a Ni−Mn−O solid solution with strong interactions. 42,44 Over NM-0.25A with Al species, the reduction peaks of Mn within Mn 2 O 3 and Mn 3 O 4 became significantly weaker, suggesting that there were less species of Mn 2 O 3 and Mn 3 O 4 and which was consistent with the weakened peaks in XRD. Meanwhile the reduction peak of Ni latt species in NiMn 2 O 4 at 773 °C also decreased, suggesting that the NiMn 2 O 4 spinel can be incorporated by Al species in a form of Ni(Mn,Al) 2 O 4 and hindered the reduction, as suggested by XRD; a very weak peak emerged at 343 °C that can be ascribed to the reduction of trace surface NiO x species (Ni surf ).…”

“…The reduction routes of Mn 2 O 3 , Mn 3 O 4 , and NiMn 2 O 4 can be categorized as Mn 2 O 3 → Mn 3 O 4 → MnO 39 and NiMn 2 O 4 → NiO + MnO → Ni + MnO. 42,43 For the NM catalyst presented in Figure 8(1) with phases of Mn 2 O 3 /Mn 3 O 4 /NiMn 2 O 4 , because of the high content of manganese, the reduction peaks of Mn within Mn 2 O 3 and Mn 3 O 4 overlapped and merged into one peak at about 529 °C; meanwhile, the reduction peak at 739 °C can be ascribed to species of lattice nickel (Ni latt ) within NiMn 2 O 4 , which can be considered as a Ni−Mn−O solid solution with strong interactions. 42,44 Over NM-0.25A with Al species, the reduction peaks of Mn within Mn 2 O 3 and Mn 3 O 4 became significantly weaker, suggesting that there were less species of Mn 2 O 3 and Mn 3 O 4 and which was consistent with the weakened peaks in XRD.…”

Magnetic and Characterization Studies of CoO/Co3O4 Nanocomposite

“…It is understood that the characteristic bands of single and/or mixed oxides in the 1000 and 400 cm −1 ranges are usually attributed to the vibration of metallic ions in the crystal lattice [29]. The spinel materials, however, are known to have two fundamental IR active modes in the vibration spectrum, which are high frequency bands around 600 cm −1 at the tetrahedral (A) site and low frequency bands around 400 cm −1 at octahedral (B) sites [30]. The bands in the obtained spectrum at 513 and 643 cm −1 are correlated with vibrations of both the Co 3+ in an octahedral hole and the Co 2+ in a tetrahedral hole in the spinel lattice, respectively [31,32].…”

Study of the Active Sites in Porous Nickel Oxide Nanosheets by Manganese Modulation for Enhanced Oxygen Evolution Catalysis

“…As shown in Figure S11, a strong and sharp absorption peak at around 425 cm –1 is attributed to an e g electron in the antibonding orbital . The FTIR band at 1384 cm –1 can be assigned to the nitrate vibrations . The broad band at 3438 cm –1 and weak band at 1633 cm –1 are attributed to the surface absorption −OH stretching vibration and bending vibration, respectively.…”

“…33 The FTIR band at 1384 cm −1 can be assigned to the nitrate vibrations. 34 The broad band at 3438 cm −1 and weak band at 1633 cm −1 are attributed to the surface absorption −OH stretching vibration and bending vibration, respectively. The FTIR bands with four absorption bands in the region of 900− 1250 cm −1 are assigned to the characteristic absorption peak of Nafion.…”