Kinetics of Mn2O3 digestion in H2SO4 solutions

Walanda, Daud K.; Lawrance, Geoffrey A.; Donne, Scott W.

doi:10.1016/j.jssc.2009.02.034

Cited by 18 publications

(14 citation statements)

References 17 publications

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“…Albeit some diffraction peaks from the XRD patterns of LM-14h and LM-22h (2θ = 21.9°, 37.1°, 40.5°, and 56.0°) can be indexed by a γ-MnO 2 phase already found by Si et al, additional peaks characteristic of such phase are missing. In literature, De Wolff et al suggested that the γ-MnO 2 structure was built from microscopic intergrowths of ramsdellite and pyrolusite (β-MnO 2 ) phases, forming an alternation of (1 × 2) and (1 × 1) tunnels [38,39]. One model was further proposed by Chabre and Pannetier [40], which allowed a successful correlation between structural features and surface properties.…”

Section: Crystal Phase Structurementioning

confidence: 99%

Hierarchical porous ε-MnO2 from perovskite precursor: Application to the formaldehyde total oxidation

Dhainaut

Rochard

et al. 2020

Chemical Engineering Journal

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A simple template-free method, based on a mineral acid etching process using manganite perovskite (LaMnO 3) as precursor, was successfully developed to obtain a series of 3D meso/macro-porous materials. The LaMnO 3 transformation was fully investigated using ICP, XRD, N 2 physisorption, TPR, TPD, SEM, TEM/EDS and XPS. This transformation proceeds through a soft-chemical process involving the dissolution of trivalent lanthanum and manganese from the perovskite structure and the dismutation of Mn 3+ cations into MnO 2 and Mn 2+ species. Strength and oxidizing properties of the acid used as modifying agent strongly impact textural and redox surface properties of the resulting materials. Specifically, extending the acid etching duration promotes the surface area and pore volume of the materials while developing interconnected macro-mesoporous networks. In our case, this soft process allowed us to obtain the ε-MnO 2 phase with hierarchical porosity without any template. Superior catalytic properties of ε-MnO 2 were observed toward HCHO oxidation as well as a good catalytic stability with respect to other macro-mesoporous counterparts. In the light of the experimental results, such performances can be related to the formation of a meso/macro-porous structure conferring high surface area and good accessibility of the active surface sites. The latter exhibit greater redox ability of the manganese species and a higher density of active surface oxygen species with respect to the perovskite precursor.

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Section: Crystal Phase Structurementioning

confidence: 99%

Hierarchical porous ε-MnO2 from perovskite precursor: Application to the formaldehyde total oxidation

Dhainaut

Rochard

et al. 2020

Chemical Engineering Journal

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“…The results of X-ray diffraction measurements are given in The dissolution step is based on the stability of soluble Mn 3 + in low pH solution in the Pourbaix diagram. It has been shown [25] that there is a short induction period before the transformation into Mn 2 O begins. The origin of this induction period is probably a saturation of the electrolyte with Mn 3 + as a result of Mn 2 O 3 dissolution before disproportionation occurs.…”

Section: Resultsmentioning

confidence: 99%

Carbon/λ-MnO2 composites for supercapacitor electrodes

Malak-Polaczyk

Ghimbeu

Vix‐Guterl

et al. 2010

Journal of Solid State Chemistry

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“…In the meantime, two other samples prepared with the molar ratio of Mn:Mn(AC) 2 = 1 and 0.5 were obtained by changing the Mn powder mass and they were denoted as D02 and D03, respectively. Then the products were dispersed in 0.7 mol L −1 H 2 SO 4 for 4 days to obtain the γ‐MnO 2 phase. Finally, the black sample was separated from the pink transparent acid solution, washed to neutral and dried at 60 °C overnight.…”

Section: Methodsmentioning

confidence: 99%

Shape‐controlled nanocrystal γ‐MnO₂: Preparation and electrochemical features

et al. 2013

Physica Status Solidi (a)

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The shape-controlled star-like and rod-like g-MnO 2 nanocrystals are prepared by vitriolization of synthesized manganese oxides with the adjustment of the molar ratio of Mn precursors in the ammonia solution. The properties of the product, g-MnO 2 , are investigated by scanning electron microscopy, X-ray powder diffraction, transmission electron microscopy, etc. The prepared rod-like g-MnO 2 nanocrystals have a high surface area of 129 cm 2 g À1 . Charge/discharge tests of the obtained nanorods particle shows a capacitance of 218 F g À1 but with a high capacitance of 261 F g À1 at the first cycle. The star-like nanoparticles show a better stability with less capacitance loss.The scheme of the phase transition of the manganese oxides. a status solidi www.pss-a.com physica ß

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Kinetics of Mn2O3 digestion in H2SO4 solutions

Cited by 18 publications

References 17 publications

Hierarchical porous ε-MnO2 from perovskite precursor: Application to the formaldehyde total oxidation

Hierarchical porous ε-MnO2 from perovskite precursor: Application to the formaldehyde total oxidation

Carbon/λ-MnO2 composites for supercapacitor electrodes

Shape‐controlled nanocrystal γ‐MnO₂: Preparation and electrochemical features

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Kinetics of Mn2O3 digestion in H2SO4 solutions

Cited by 18 publications

References 17 publications

Hierarchical porous ε-MnO2 from perovskite precursor: Application to the formaldehyde total oxidation

Hierarchical porous ε-MnO2 from perovskite precursor: Application to the formaldehyde total oxidation

Carbon/λ-MnO2 composites for supercapacitor electrodes

Shape‐controlled nanocrystal γ‐MnO2: Preparation and electrochemical features

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Product

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Shape‐controlled nanocrystal γ‐MnO₂: Preparation and electrochemical features