Catalytic properties of La1 $minus; xA$prime;xFeO3(A$prime; = Sr,Ce) and La1 $minus; xCexCoO3

Nitadori, Taihei; Misono, Makoto

doi:10.1016/0021-9517(85)90193-9

Cited by 157 publications

(60 citation statements)

References 7 publications

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“…This is consistent with the TPD and TPR results, most of which show no desorption peak for β-oxygen up to the highest temperatures probed (1273 K). [38][39][40][41][42][43]46 Instead of surface oxygen vacancies, secondary phases were observed at 850-1250 K, which is also consistent with our predictions. 40,46 For adsorbed oxygen atoms (O low ), the TPD and TPR experiments on LFO generally show two different trends based on the calcination temperature of the ceramic.…”

Section: Relation To Experimental Resultssupporting

confidence: 90%

“…In the case of LFO calcined below 923 K, desorption for α-oxygen was clearly observed. In particular, 46 In contrast, at a high calcination temperature of 1123 K, most of the experiments reported no desorption peak of α-oxygen, [41][42][43] even though weak peaks below 773 K were observed by Nitadori et al 39 For convenience, in the following discussion temperatures of 973 K or less will be defined as "low calcination temperatures" and those at 1123 K or higher will be defined as "high calcination temperatures".…”

Section: Relation To Experimental Resultsmentioning

confidence: 97%

“…[38][39][40][41][42][43] Even though the kinetic factors in the TPD and TPR results were not considered during the development of our surface phase diagrams, it is reasonable to expect that the desorption peaks of so called α-and β-oxygen atoms 41 Figure 2). …”

Section: Relation To Experimental Resultsmentioning

confidence: 99%

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Stoichiometry of theLaFeO3(010) surface determined from first-principles and thermodynamic calculations

et al. 2011

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The phase diagram of LaFeO 3 (010) surfaces is developed by Ab-initio thermodynamics.The stabilities of LaO-and FeO 2 -terminated surfaces are investigated at temperatures representative of solid oxide fuel cell (SOFC) operating conditions (773 K, 1073 K, and 1223For LaO-type surfaces, it is predicted that the most stable surface structure is oxidized at all temperatures considered. For FeO 2 -type surfaces, the most stable surface structure is predicted to change from oxidized (at 773 K) to stoichiometric (at 1073 and 1223 K). Even though both LaO and FeO 2 surfaces can be oxidized under SOFC operating conditions, the degree of oxidation is much greater for the LaO surface. In addition, as reduced surfaces are predicted to be significantly more unstable than stoichiometric and oxidized terminations at these temperatures and oxygen partial pressures, surface oxygen vacancies are not predicted to form on either the LaO or the FeO 2 terminations. Moreover, by increasing temperatures (above ~1500 K at p(O 2 ) = 0.21atm), only FeO 2 -type surfaces are predicted to be stable. Importantly, the calculated transition temperatures where surface oxygen stoichiometries are predicted to change are in good agreement with the results of temperature-programmed desorption experiments.

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Section: Relation To Experimental Resultssupporting

confidence: 90%

Section: Relation To Experimental Resultsmentioning

confidence: 97%

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Stoichiometry of theLaFeO3(010) surface determined from first-principles and thermodynamic calculations

et al. 2011

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“…For instance, Misono et al [5][6][7] highlighted two peaks upon heating in TPD experiments on perovsiktes: α, due to the low-temperature release from the surface of oxygen deriving from O -and O 2-species, and β, occurring at higher temperature, due to O 2-species from the bulk.…”

Section: Introductionmentioning

confidence: 99%

Oxygen transport in nanostructured lanthanum manganites

Rossetti

Allieta

Biffi

et al. 2013

Phys. Chem. Chem. Phys.

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Methods and models describing oxygen diffusion and desorption in oxides have been developed for slightly defective and well crystallised bulky materials. Does nanostructuring change the mechanism of oxygen mobility? In such a case, models should be properly checked and adapted to take into account new material properties.In order to do so, temperature programmed oxygen desorption and thermogravimetric analysis, either in isothermal or ramp mode, have been used to investigate some nanostructured La 1-x A x MnO 3±δ samples (A=Sr and Ce, 20-60 nm particle size) with perovskite-like structure. The experimental data have been elaborated by means of different models to define a set of kinetic parameters able to describe oxygen release properties and oxygen diffusion through the bulk. Different rate-determining steps have been identified, depending on the temperature range and oxygen depletion of the material. In particular, oxygen diffusion shows rate-limiting at low temperature and with low defect concentration, whereas oxygen recombination at the surface seems to be the rate-controlling step at high * Corresponding author: Fax: +39-02-50314300; e-mail: ilenia.rossetti@unimi.it 2 temperature. However, the oxygen recombination step is characterised by an activation energy much lower than that for diffusion.In the present paper oxygen transport in nanosized materials is quantified by making use of widely diffused experimental techniques and by critically adapting to nanoparticles suitably chosen models developed for bulk materials.

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“…The results confirm the catalytic activity of perovskite oxides because the methane oxidation starts already at 400 • C. In addition, the partial substitution of lanthanum with strontium increase the catalytic activity because at 600 • C the unsubstituted LaFeO 3 leads to a methane conversion of 25%, while the substituted La 0.8 Sr 0.2 FeO 3 and La 0.6 Sr 0.4 FeO 3 leads to a higher methane conversion of 65% and 35% respectivelly. The lower catalytic activity of the higher Sr-substituted perovskite is due to the structural and valece changes, leading to lower reductin/oxidation capability from the relative rate of dissociation and bulk diffusion of oxide ions [32]. Since the initial stage of the sigmoidal curve is related to a kinetically controlled regime [30,33], the rate of methane combustion was calculated from the conversion values lower than 20% accordingly with equation r = (F gas · X CH4 ) / (V ST P · m cat ), where r(mol·s −1 ·g −1 ) is the reaction rate, F gas (L·s −1 ) is the inlet flow of reactants in, X CH4 is the fractional conversion, V ST P (22.414 L·mol −1 ) is the volume occupied by one mole of gas at Standard Temperature and Pressure condition, m cat (g) is the mass of catalyst.…”

Section: -6mentioning

confidence: 99%

Catalytic combustion of methane by perovskite-type oxide nanoparticles as pollution prevention strategy

Zaza¹,

Luisetto²,

Serra³

et al. 2016

AIP Conference Proceedings

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Catalysis science offers to combustion technology significant opportunity to increase the fuel efficiency by lowering the internal temperature gradients and reduce the environmental impact by lowering local peak temperature and, consequently, thermodynamically inhibiting the nitrogen oxides formation. Alternative catalytic materials are transition metals oxide, including complex oxides with perovskite crystalline structure. The aim of this work is to synthetize lanthanum ferrite perovskites with lanthanum ions partially substituted by strontium ions in order to study the substitution effects on structural properties and redox activity of the original oxide. Lanthanum ferrite oxides partially substituted with different Strontium amount were synthesized by solution combustion method. The perovskite nanopowders obtained were characterized by XRD, SEM, TPR analyses for defining crystalline structure, morphology and redox properties. Finally, the catalytic activity for methane combustion was tested. The most performing catalysts was La0:6Sr0:4FeO3 having the highest oxygen vacancy concentration as revealed byTPR analysis

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Catalytic properties of La1 $minus; xA$prime;xFeO3(A$prime; = Sr,Ce) and La1 $minus; xCexCoO3

Cited by 157 publications

References 7 publications

Stoichiometry of theLaFeO3(010) surface determined from first-principles and thermodynamic calculations

Stoichiometry of theLaFeO3(010) surface determined from first-principles and thermodynamic calculations

Oxygen transport in nanostructured lanthanum manganites

Catalytic combustion of methane by perovskite-type oxide nanoparticles as pollution prevention strategy

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