Fe3−xMnxO4 catalysts: phase transformations and carbon monoxide oxidation

The distinct effects of Mn substitution on the reactivity of magnetite in heterogeneous Fenton reaction and Pb(II) adsorption

“…Mn cations initially occupy the octahedral sites in the bulk structure, accelerate the electron transfer and improve the catalytic activity of magnetite, which is in accordance with previous studies in Refs. [13,23]. But with an increase in Mn content, partial Mn cations occupy the octahedral sites on magnetite surface.…”

“…The octahedral Mn 2+ and Mn 3+ accelerate the electron transfer to regenerate the Fenton active species Fe 2+ , which leads to the strong Fenton activity of FM1 (Fig. A.1) [13,23]. Moreover, the catalytic performance of magnetites with lower Mn substitution than FM1 (Table A.1) was tested in the AOII degradation.…”

“…The introduction of Co [13], Ti [19,20], V [18] and Cr [21] improves the Fenton catalytic activity of magnetite, while Ni shows an inhibitory effect [13]. Such distinct effects greatly depend on the oxidation states and occupancy of substituting cations [22,23]. Therefore, the experimental determination of cation distribution in the spinel structure and their oxidation states is an interesting challenge.…”

Nanosized Cation-Deficient Fe−Ti Spinel: A Novel Magnetic Sorbent for Elemental Mercury Capture from Flue Gas

“…5,6 Spinel ferrites are of great fundamental and technological importance due to their structural, electronic, magnetic, and catalytic properties. 7 An interesting feature of spinel ferrites is the possibility to replace iron cations by other metal cations while maintaining the spinel structure. 8 The physicochemical properties of spinel ferrites are strongly dependent on the site, nature, and amount of metal incorporated into the structure.…”

A comparative study about the effects of isomorphous substitution of transition metals (Ti, Cr, Mn, Co and Ni) on the UV/Fenton catalytic activity of magnetite

“…Ti 4+ [8], Cr 3+ [9], Mn 2+ [10], Co 2+ [11], and Ni 2+ [10]. Previous studies have investigated the effect of above substitutions on the heterogeneous Fenton catalytic activity of magnetite, which was greatly dependent on the occupancy, nature and amount of substituting metals [12][13][14]. For example, the catalytic activity relied on the octahedral cations rather than the tetrahedral ones, as the octahedral sites were almost exclusively exposed at the surface of inverse spinel structure [14].…”