Point defects diagrams for pure and doped manganese oxide Mn1−δO in the temperature range of 1173–1830 K

Stokłosa, Andrzej

doi:10.1016/j.matchemphys.2012.04.006

Cited by 6 publications

(14 citation statements)

References 43 publications

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“…which, as can be seen, is compatible with the analogic sum calculated from the value of the electrical conductivity ((•,○) points) (Stokłosa, 2012). The minimum of this function overlaps with the minimum of the electrical conductivity (Eror & Wagner, 1971;Hed & Tannhauser, 1967).…”

Section: δGsupporting

confidence: 77%

“…Empty points denote the values obtained for the model of the structure of simple defects (vac) without complexes (Stokłosa, 2012). As shown in Figure (Hed & Tannhauser, 1967a and (Fender & Riley, 1970), as well as by (Carel, 1982;Gavarri et al, 1985).…”

Section: δGmentioning

confidence: 93%

“…', also with lower ionization degrees, formed according to the reactions (7) - (12) ΔG of the formation of electronic defects were determined according to the relation (Stokłosa, 2012):…”

Section: δGmentioning

confidence: 99%

“…As a result, a simplified electroneutrality condition is used. It was also shown (Stokłosa, 2011(Stokłosa, , 2012 that the inclusion of the interstitial cations (neglected so far) in the model of the defects structure dramatically changes the calculated…”

Section: Introductionmentioning

confidence: 97%

“…In the previous works (Stokłosa, 2011a(Stokłosa, , 2011b(Stokłosa, , 2012, the calculations of the diagrams of the concentrations of point defects were performed, for Co 1-δ O, Ni 1-δ O and Mn 1-δ O, using the results of the studies of the deviation from the stoichiometry by different authors, assuming as a first approximation that there are cation vacancies and interstitial metal ions with different ionization degrees. A new method was used there for the calculations of the diagrams.…”

Section: Introductionmentioning

confidence: 99%

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Defect Complexes and Defect Clusters in Mn1-deltaO, Co1-deltaO and Ni1-deltaO Oxides Diagrams of the Concentrations of Point Defects

Stokłosa¹

2012

IJC

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The diagrams of the concentrations of point defects, determined for a series of temperatures, for the oxides: Mn 1-δ O, (1173-1830 K), Co 1-δ O (1223-1673 K) and Ni 1-δ O (1273-1673 K), whilst taking into consideration simple defects and defect clusters of type (2:1), (4:1), (6:2), are presented in this work. A new method was used for the calculations of the diagrams and the results of the studies of the deviation from the stoichiometry obtained by many authors were used in the calculations. The values of Go of the formation of the individual defects and clusters were determined; their temperature dependencies were also determined. The calculations show that in the studied oxides the maximal concentration of defect clusters is lower than the concentration of single-ionized cation vacancies. At the lowest temperatures studied, the concentration of clusters is comparable to the concentration of electroneutral vacancies. The ratio of these concentration decreases with the temperature increase. The presence of defect clusters only slightly decreases the concentration of cation vacancies. The ratio of the concentrations of defect clusters varies with the temperature. This ratio is different for the individual oxides.

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Section: δGsupporting

confidence: 77%

Section: δGmentioning

confidence: 93%

“…', also with lower ionization degrees, formed according to the reactions (7) - (12) ΔG of the formation of electronic defects were determined according to the relation (Stokłosa, 2012):…”

Section: δGmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Defect Complexes and Defect Clusters in Mn1-deltaO, Co1-deltaO and Ni1-deltaO Oxides Diagrams of the Concentrations of Point Defects

Stokłosa¹

2012

IJC

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Enhanced Coke Gasification Activity of the Mn_1.5Cr_1.5O₄ Spinel Catalyst during Coking in Ethylene–Steam Mixtures

et al. 2021

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Mn−Cr−O spinel catalysts (MnCr 2 O 4 and Mn 1.5 Cr 1.5 O 4 ) and single oxides of Mn and Cr are coked under ethylene and ethylene−steam mixtures to simulate reaction conditions occurring in steam cracker furnaces. The coking rates are measured using thermogravimetric analysis, and the Mn 1.5 Cr 1.5 O 4 catalyst displayed considerably less coke deposition (an order of magnitude) under ethylene−steam flow. Analysis of the outlet gas flow suggests the Mn 1.5 Cr 1.5 O 4 catalyst gasified the radically formed coke into carbon oxides without significantly affecting ethylene conversion. The anticoking performance of the Mn 1.5 Cr 1.5 O 4 catalyst is attributed to the presence of Mn 3+ species in the spinel phase structure that are active for coke gasification in the presence of steam. No significant changes in structure or performance are observed for the Mn 1.5 Cr 1.5 O 4 catalyst across several coking and decoking cycles. The Mn−Cr−O spinel oxide with higher Mn content is suggested to have desirable activity and stability to limit coke deposition during steam cracking.

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Gasification of Radical Coke with Steam and Steam–Hydrogen Mixtures over Manganese–Chromium Oxides

Bukhovko

Liu

et al. 2020

Ind. Eng. Chem. Res.

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The coke gasification performance of synthesized Mn−Cr−O catalysts, as well as MnO x , Cr 2 O 3 , and α-Al 2 O 3 , is evaluated in the presence of steam and steam−hydrogen mixtures. Radical coke is deposited in situ onto the catalysts via ethylene pyrolysis at an elevated temperature. Raman spectroscopy analysis reveals that the coke deposited on the various catalysts is similar in nature across all catalysts. Rates of coke gasification are determined from thermogravimetric analysis (TGA) using different gas/vapor feeds including inert/steam and steam/hydrogen mixtures. Addition of hydrogen to a steam feed results in a considerable reduction in reaction rates, suggesting that hydrogen inhibits the production of surface oxygen that is needed for coke gasification. Active Mn 3+ species on the surface of Mn-rich spinel (Mn 1.5 Cr 1.5 O 4 ) and MnO catalysts are hypothesized to be responsible for the significantly higher reaction rates and lower apparent activation barriers for coke gasification under mixed steam−hydrogen conditions.

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Point defects diagrams for pure and doped manganese oxide Mn1−δO in the temperature range of 1173–1830 K

Cited by 6 publications

References 43 publications

Defect Complexes and Defect Clusters in Mn1-deltaO, Co1-deltaO and Ni1-deltaO Oxides Diagrams of the Concentrations of Point Defects

Defect Complexes and Defect Clusters in Mn1-deltaO, Co1-deltaO and Ni1-deltaO Oxides Diagrams of the Concentrations of Point Defects

Enhanced Coke Gasification Activity of the Mn_1.5Cr_1.5O₄ Spinel Catalyst during Coking in Ethylene–Steam Mixtures

Gasification of Radical Coke with Steam and Steam–Hydrogen Mixtures over Manganese–Chromium Oxides

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Point defects diagrams for pure and doped manganese oxide Mn1−δO in the temperature range of 1173–1830 K

Cited by 6 publications

References 43 publications

Defect Complexes and Defect Clusters in Mn1-deltaO, Co1-deltaO and Ni1-deltaO Oxides Diagrams of the Concentrations of Point Defects

Defect Complexes and Defect Clusters in Mn1-deltaO, Co1-deltaO and Ni1-deltaO Oxides Diagrams of the Concentrations of Point Defects

Enhanced Coke Gasification Activity of the Mn1.5Cr1.5O4 Spinel Catalyst during Coking in Ethylene–Steam Mixtures

Gasification of Radical Coke with Steam and Steam–Hydrogen Mixtures over Manganese–Chromium Oxides

Contact Info

Product

Resources

About

Enhanced Coke Gasification Activity of the Mn_1.5Cr_1.5O₄ Spinel Catalyst during Coking in Ethylene–Steam Mixtures