EPR and XRD as probes for activity and durability of LaMnO3 perovskite-like catalysts

Oliva, Cesare; Forni, L.

doi:10.1016/s1566-7367(00)00003-0

Cited by 18 publications

(20 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, it has been also shown there that this difference explains the higher oxygen mobility present in the Ni -based catalyst and, therefore, its higher activity for methane CFC at T> 673 K (i.e., when the intrafacial mechanism is active). This confirms what was already reported with LaMnO3+S samples [15]: more active catalysts are generally characterized by greater amounts of oxygen vacancies and, therefore, by broader EPR linewidths.…”

Section: Discussionsupporting

confidence: 91%

EPR investigation of superparamagnetism in nanometric-size LaFeO3±δ and La2NiO4±δ perovskites

Oliva

Forni

2001

Appl. Magn. Reson.

Self Cite

View full text Add to dashboard Cite

Two LaFeO3 ,,, and La2NiO4+ó catalysts characterized by high thermal stability and phase purity have been prepared. Scanning electron microscopy analysis showed that they consisted of 20-60 nm spheroids, generally clustered in one order of magnitude larger particles. Electron paramagnetic resonance (EPR) spectroscopy showed that both samples possess superparamagnetic properties, connected with ca. 20 nm diameter particles. Furthermore, the EPR patterns were broader in La2NiO4 , 5 than in LaFeO3+8, indicating a greater amount of local disorder in the former. This was attributed to the presence of more oxygen vacancies in the Ni-based than in the Fe-based sample, in agreement with what was elsewhere hypothesized on the basis of catalytic properties of the two samples for the flameless combustion of methane.

show abstract

Section: Discussionsupporting

confidence: 91%

EPR investigation of superparamagnetism in nanometric-size LaFeO3±δ and La2NiO4±δ perovskites

Oliva

Forni

2001

Appl. Magn. Reson.

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, activity through the intra-facial mechanism is mainly due to the presence of lattice defects, whose concentration depends on temperature and duration of the calcination step during preparation. The FH technique adopts very short residence time in a high temperature flame and since defects concentration depend on the calcination temperature more than on its duration, one has to expect a lower concentration of defects in the FH than in the SG sample, influencing the intra-facial activity [22].…”

Section: Catalytic Activitymentioning

confidence: 99%

Effect of preparation method on activity and stability of LaMnO and LaCoO catalysts for the flameless combustion of methane

Campagnoli

Tavares

Fabbrini

et al. 2005

Applied Catalysis B: Environmental

109

View full text Add to dashboard Cite

A set of LaMnO3 and LaCoO3 catalysts was prepared through different synthesis procedures. The selected techniques included the sol-gel method, flame hydrolysis from aqueous solution, complexation through EDTA and solid-state reaction. The last was accomplished through reactive grinding by ball milling either in a vibration mill or in a planetary mill. EDTA complexation was applied for LaCoO3 only and did not improve significantly catalyst activity or stability, with respect to other techniques. Ball milling never allowed obtaining a pure perovskitic phase, at least under the most energetic grinding conditions permitted by our apparatus. The highest activity for the catalytic flameless combustion of methane was obtained with the sol-gel prepared samples, though thermal resistance revealed insufficient for high temperature applications. A bit lower activity, but coupled with good thermal stability was obtained with the samples prepared through flame hydrolysis.

show abstract

“…For this purpose, a complete picture of the thermodynamic stability of LaMnO 3 has been studied extensively by experiment (with X-ray [6][7][8][9][10][11] and neutron diffraction [7,12], scanning [10,11] and transmission electron microscopy [10], electron paramagnetic resonance [9], thermogravimetry (TG) [6,10,12,13], differential thermal analysis (DTA) [11,12], differential scanning [6,8,10] and alternating current calorimetry [8]). However, not much literature can be found that investigates the factors affecting the reactivity of LaMnO 3 as a catalyst in an AFC environment [14].…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic stability of LaMnO3and its competing oxides: A hybrid density functional study of an alkaline fuel cell catalyst

et al. 2011

View full text Add to dashboard Cite

The phase stability of LaMnO 3 with respect to its competing oxides is studied using hybridexchange density functional theory (DFT) as implemented in CRYSTAL09. The underpinning DFT total energy calculations are embedded in a thermodynamic framework that takes optimal advantage of error cancellation within DFT. It has been been found that by using the ab initio thermodynamic techniques described here, the standard Gibbs formation energies can be calculated to a significantly greater accuracy than was previously reported (a mean error of 1.6% with a maximum individual error of -3.0%). This is attributed to both the methodology for isolating the chemical potentials of the reference states, as well as the use of the B3LYP functional to thoroughly investigate the ground state energetics of the competing oxides.

show abstract

EPR and XRD as probes for activity and durability of LaMnO3 perovskite-like catalysts

Cited by 18 publications

References 12 publications

EPR investigation of superparamagnetism in nanometric-size LaFeO3±δ and La2NiO4±δ perovskites

EPR investigation of superparamagnetism in nanometric-size LaFeO3±δ and La2NiO4±δ perovskites

Effect of preparation method on activity and stability of LaMnO and LaCoO catalysts for the flameless combustion of methane

Thermodynamic stability of LaMnO3and its competing oxides: A hybrid density functional study of an alkaline fuel cell catalyst

Contact Info

Product

Resources

About