Equilibrium Pressures of Oxygen over Mn[sub 2]O[sub 3]-Mn[sub 3]O[sub 4] at Various Temperatures

Otto, Earl M.

doi:10.1149/1.2426068

Cited by 25 publications

(5 citation statements)

References 8 publications

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“…For the lowest two temperatures (441 ~ and 491~ the apparatus was identical with that previously described by this author (41). A diagrammatic sketch of the apparatus is shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

“…Since the range in oxygen pressure exceeded 100 arm, it is necessary to use fugacity (fO2) in calculating values for thermodynamic constants (heat and entropy) of the reaction to give precise correlation of pressure and temperature. In other respects the treatment of the data is similar to that used in the previous paper (41). The method of Prosen (42) was again used to convert the data to yield a theoretical straight line plot of AY°/T against l/T, where this line is the tangent to the AF°/T curve at a selected temperature of 813°K, an approximate midpoint temperature in this study.…”

Section: Treatment Of Datamentioning

confidence: 99%

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Equilibrium Pressures of Oxygen over MnO[sub 2]-Mn[sub 2]O[sub 3] at Various Temperatures

Otto

1965

J. Electrochem. Soc.

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Oxygen pressures of the pyrolusite form of MnO2 have been determined in a temperature range of 441°–642°C. The dissociation reaction 4MnO2false(normalcfalse)⇄2Mn2O3false(normalcfalse)+O2false(normalgfalse) has been found to reach a steady state in the forward direction; reaction in the reverse direction was exceedingly slow and did not reach a steady state. normalΔH° and normalΔS° for the reaction at 813°K are 37.87 kcal and 51.28 cal/deg, respectively. With little error these values can be used in the equation −4.5756logpO2 false(normalatmfalse)=37,870/T−51.28 to calculate the pressure for any temperature in the above mentioned range. Conversion to 298.15°K resulted in normalΔH°298=38.8 normalkcal and normalΔS°298=52.8 normalcal/normaldeg for the dissociation. The limits of uncertainties are not given here because equilibria were not attained by recombination.

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“…For the lowest two temperatures (441 ~ and 491~ the apparatus was identical with that previously described by this author (41). A diagrammatic sketch of the apparatus is shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

Section: Treatment Of Datamentioning

confidence: 99%

Equilibrium Pressures of Oxygen over MnO[sub 2]-Mn[sub 2]O[sub 3] at Various Temperatures

Otto

1965

J. Electrochem. Soc.

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“…Left side shows manganese oxides phase stability diagram. Thermodynamic data extracted from ref , dashed line from ref , and dashed-dot line from data of ref . Right side, crystal structures of Mn oxides (All the crystalline structures were simulated with software Vesta).…”

Section: Thermochemical Heat Storage Based On Redox Cycles Of Metal O...mentioning

confidence: 99%

Solar Energy on Demand: A Review on High Temperature Thermochemical Heat Storage Systems and Materials

et al. 2019

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Among renewable energies, wind and solar are inherently intermittent and therefore both require efficient energy storage systems to facilitate a round-the-clock electricity production at global scale. In this context, concentrated solar power (CSP) stands out among other sustainable technologies because it offers the interesting possibility of storing energy collected from the sun as heat, by sensible, latent or thermochemical means. Accordingly, continuous electricity generation in the power block is possible even during off-sun periods, providing CSP plants with a remarkable dispatchability. Sensible heat storage has been already incorporated to commercial CSP plants. However, due to its potentially higher energy storage density, thermochemical heat storage (TCS) systems emerge as an attractive alternative for the design of next generation power plants, which are expected to operate at higher temperatures. Through these systems, thermal energy is used to drive endothermic chemical reactions, which can subsequently release the stored energy when needed through a reversible exothermic step. This review analyzes the status 2 of this prominent energy storage technology, its major challenges and future perspectives, covering in detail the numerous strategies proposed for the improvement of materials and thermochemical reactors. Thermodynamic calculations allow selecting high energy density systems, but experimental findings indicate that sufficiently rapid kinetics and long-term stability trough continuous cycles of chemical transformation are also necessary for practical implementation. In addition, selecting easy to handle materials with reduced cost and limited toxicity is crucial for large-scale deployment of this technology. In this work, the possible utilization of materials as diverse as metal hydrides, hydroxides or carbonates for thermochemical storage is discussed. Furthermore, especial attention is paid to the development of redox metal oxides, such as Co3O4/CoO, Mn2O3/Mn3O4 and perovskites of different compositions, as an auspicious new class of TCS materials due to the advantage of working with atmospheric air as reactant, avoiding the need of gas storage tanks. Current knowledge about the structural, morphological and chemical modifications of these solids, either caused during redox transformations, or induced wittingly as a way to improve their properties, is revised in detail. In addition, the design of new reactors concepts proposed for the most efficient use of TCS in concentrated solar facilities is also critically considered. Finally, strategies for the harmonic integration of these units in functioning solar power plants, as well as the economic aspects are also briefly assessed.

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“…[47,90,[94][95][96][97][98][99][100] Additionally, the experimental data have been assessed and tabulated by a number of authors [72,[101][102][103][104][105][106][107][108] (Table 11). The following values, as quoted by Kubaschewski et al, [105] were used in the experimental data file: 384.9 kJ/mol for stoichiometric Mn 1 …”

Section: Enthalpies Of Formationmentioning

confidence: 99%

Assessment of the Mn-O system

Grundy

Hallstedt

Gauckler

2003

JPE

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Experimental data on the thermodynamics and the phase diagram of the Mn-O system were reviewed, and by application of the CALPHAD method, a consistent set of thermodynamic model parameters was optimized. The phases pyrolusite (MnO 2 ), bixbyite (Mn 2 O 3 ), and hausmannite (Mn 3 O 4 ) were described as stoichiometric compounds. Manganosite (Mn 1−x O) was described using the compound-energy model and the liquid described using the two-sublattice model for ionic liquids.

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Equilibrium Pressures of Oxygen over Mn[sub 2]O[sub 3]-Mn[sub 3]O[sub 4] at Various Temperatures

Cited by 25 publications

References 8 publications

Equilibrium Pressures of Oxygen over MnO[sub 2]-Mn[sub 2]O[sub 3] at Various Temperatures

Equilibrium Pressures of Oxygen over MnO[sub 2]-Mn[sub 2]O[sub 3] at Various Temperatures

Solar Energy on Demand: A Review on High Temperature Thermochemical Heat Storage Systems and Materials

Assessment of the Mn-O system

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