Catalytic properties of stoichiometric and non-stoichiometric LaFeO3 perovskite for total oxidation of methane

Spinicci, R.; Tofanari, A.; Delmastro, A.; Mazza, Daniele; Ronchetti, Silvia Maria

doi:10.1016/s0254-0584(01)00498-9

Cited by 76 publications

(54 citation statements)

References 8 publications

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“…Based on X-ray photoelectron spectroscopy (XPS) data, we found out that the actual structure of the prepared perovskite nanoparticles was probably La 0.8 FeO 2.7 . Similar perovskite structure was also reported by Spinicci et al using low temperature thermal decomposition method [32]. The oxygen non-stoichiometry effect was common when the nanoparticles were prepared using auto-combustion, thermal-decomposition, citrate pyrolysis, solid state reaction and Pechini methods [32,[47][48][49].…”

Section: Physicochemical Characterization Of Nanoparticlessupporting

confidence: 66%

“…Similar perovskite structure was also reported by Spinicci et al using low temperature thermal decomposition method [32]. The oxygen non-stoichiometry effect was common when the nanoparticles were prepared using auto-combustion, thermal-decomposition, citrate pyrolysis, solid state reaction and Pechini methods [32,[47][48][49]. Delmastro et al [50] showed that a series of these perovskite structures (including LaFeO3 and La0.7FeO2.55) demonstrated identical XRD patterns.…”

Section: Physicochemical Characterization Of Nanoparticlessupporting

confidence: 65%

“…Among various wet chemical methods involved in the growth of LaFeO 3 nanoparticles [29], a surfactant-assisted hydrothermal process has significant advantages [30]. These advantages include high phase purity, chemical stability, large surface areas, monodispersed shape/size, low temperature growth, oxygen non-stoichiometric qualities, and cost-effectiveness over the above-mentioned spinel metal oxide nanofillers [31][32][33]. In addition, defects in ABO 3 generated from cation deficiencies in either A or B sites, or oxygen deficiency, can be easily manipulated by partial substitutions that exhibit high proton or oxygen ion conductivity [30,34].…”

Section: Introductionmentioning

confidence: 99%

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Surfactant-Assisted Perovskite Nanofillers Incorporated in Quaternized Poly (Vinyl Alcohol) Composite Membrane as an Effective Hydroxide-Conducting Electrolyte

Kumar

et al. 2017

Energies

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Perovskite LaFeO 3 nanofillers (0.1%) are incorporated into a quaternized poly(vinyl alcohol) (QPVA) matrix for use as hydroxide-conducting membranes in direct alkaline methanol fuel cells (DAMFCs). The as-synthesized LaFeO 3 nanofillers are amorphous and functionalized with cetyltrimethylammonium bromide (CTAB) surfactant. The annealed LaFeO 3 nanofillers are crystalline without CTAB. The QPVA/CTAB-coated LaFeO 3 composite membrane shows a defect-free structure while the QPVA/annealed LaFeO 3 film has voids at the interfaces between the soft polymer and rigid nanofillers. The QPVA/CTAB-coated LaFeO 3 composite has lower methanol permeability and higher ionic conductivity than the pure QPVA and QPVA/annealed LaFeO 3 films. We suggest that the CTAB-coated LaFeO 3 provides three functions to the polymeric composite: increasing polymer free volume, ammonium group contributor, and plasticizer to enhance the interfacial compatibility. The composite containing CTAB-coated LaFeO 3 results in superior cell performance. A maximum power density of 272 mW cm −2 is achieved, which is among the highest power outputs reported for DAMFCs in the literature.

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Section: Physicochemical Characterization Of Nanoparticlessupporting

confidence: 66%

Section: Physicochemical Characterization Of Nanoparticlessupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Surfactant-Assisted Perovskite Nanofillers Incorporated in Quaternized Poly (Vinyl Alcohol) Composite Membrane as an Effective Hydroxide-Conducting Electrolyte

Kumar

et al. 2017

Energies

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“…At temperatures higher 650 °C it is observed the beginning of a H 2 consumption that does not end up to 800 °C. It has been reported previously that LaFeO 3 perovskites are remarkably stable towards reduction [18][19][20] . Therefore, this hydrogen consumption is likely related to the second step reduction of the Fe perovskite leading to the collapse of the perovskite structure with the formation of Fe metal, La 2 O 3 and small amounts of MnO and Mo.…”

Section: Controlled Reduction Of the Prepared Perovskitementioning

confidence: 89%

Controlled reduction of LaFe xMn yMo zO3/Al2O3 composites to produce highly dispersed and stable Fe0 catalysts: a Mössbauer investigation

et al. 2008

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were prepared and characterized by XRD, BET, TPR, SEM and Mössbauer spectroscopy. XRD for unsupported perovskite showed the formation of a single phase perovskite structure. The Mössbauer spectra of the perovskites were fitted with hyperfine field distribution model for the perovskite. Supported perovskites on Al 2 O 3 showed a decrease of the hyperfine field in respect to unsupported perovskite, due to decrease of particle size and dispersion of the Fe 3+ specimens on the support. Also showed broaden lines and relaxation effects due to the small particle size. To produce the Fe 0 catalyst, the composite perovskite(25%)/Al 2 O 3 was reduced with H 2 at 900, 1000 and 1100 °C for 1 hour. XRD (Figure 1). This catalyst has been recently investigated for the synthesis of single wall carbon nanotube showing promising results 14. This preparation method shows several potential advantages: i) should allow a good control of the metallic particle size distribution, ii) should improve the thermal stability to the catalyst due to a strong matrix insulation effect (La 2 O 3 and Al 2 O 3 should keep Fe o particles well separated), iii) the precursor elements and stoichiometry can be adjusted to produce catalysts with different metals and different ratios, iv) the metals present in the precursor, e.g. Fe and Mo, should be homogeneously distributed throughout the oxide and produce welldefined metallic particles, and v) the dispersion of the metal particle can be further controlled by the reduction conditions. ) was used. The perovskites were prepared by the reaction of 0.5 mol of citric acid (CA) dissolved in 2 mol of water at 60 °C, followed by the addition of 1 mmol of La(NO 3 ) 3 .6H 2 O and different proportions of the other metals such as Fe(NO 3 ) 3 .9H 2 O, Mn(NO 3 ) 2 .4H 2 O and Mo(acac) 2 O 2 (acac acethylacetonate) in order to produce the desired stoichiometry. The mixture was stirred for about 2 hours, until a clear orange solution of the stable metal-CA complexes is obtained. After the complete dissolution, 400 mmol of ethylene glycol (EG) followed by the addition of the Al 2 O 3 nanopowder in amounts to obtain composites with 25, 33 and 50 wt (%) of perovskite on alumina. The suspension was continuously stirred while the temperature was slowly increased to 90 °C. This step removes the excess of water and allows the polyesterification reaction between CA and EG to be further activated. The prolonged heating at 90 °C occurs for 7 hours and resulted in a viscous orange mass 15 . This resin was then treated at 400-450 °C in air for 2 hours for the charring. The final product, a dark brown powder was ground and then calcined at 800 °C in air for 6 hours. Experimental ProceduresThe powder XRD data were obtained in a Rigaku model Geigerflex equipment using Co Kα radiation scanning from 10 to 80° (2θ) at a scan rate of 4° min -1. Silicon was used as an external standard.

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“…This result is likely related to the higher activity of LaMnO 3 compared to LaFeO 3 for total oxidation, as reported in the literature. 22,23 On the other hand, the higher activity observed for the perovskite LaFe 0.27 Mn 0.73 O 3 suggests a special effect of the combination of small amounts of Fe with Mn. However, more detailed studies are necessary to understand the effect of Fe in the catalytic reaction.…”

mentioning

confidence: 99%

LaFe xMn yMo zO 3 catalysts for the oxidation of volatile aromatic organic contaminants

Tristão¹,

Ardisson²,

Macedo³

et al. 2007

J. Braz. Chem. Soc.

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Novas perovskitas mistas LaFe x Mn y Mo z O 3 foram preparadas, caracterizadas e investigadas como catalisadores para a oxidação total de tolueno, usado como composto orgânico aromático volátil (COV aromático) modelo. As perovskitas foram caracterizadas por DRX (Difratometria de Raios X), RTP (Redução a Temperatura Programada), determinação de área superficial BET e espectroscopia Mössbauer. Os dados obtidos indicaram a formação da fase perovskita e a incorporação de todos os metais na estrutura. As reações catalíticas foram realizadas em um sistema de Reação a Temperatura Programada com tolueno (1000 ppm) e ar sintético em fase gasosa. Foi observado que a oxidação do tolueno inicia-se a 280 o C e que Mn é o principal responsável pela atividade catalítica. No entanto, a presença de pequenas quantidades de Fe (LaFe 0,27 Mn 0,73 O 3 ) resulta em um importante aumento nessa atividade. Estudos de tempo de vida mostraram que os catalisadores são estáveis mesmo após 100 h de reação a 400 o C e nenhuma alteração estrutural significativa foi observada por DRX e Mössbauer.New mixed perovskites LaFe x Mn y Mo z O 3 were prepared, characterized and investigated as catalysts for the total oxidation of the model aromatic VOC (Volatile Organic Compound), toluene. The perovskites were characterized by XRD (X-Ray Diffractometry), Mössbauer spectroscopy, TPR (Temperature Programmed Reduction) and BET surface area determination. The results suggested the formation of the perovskite phase with incorporation of all metals in the structure. The catalytic studies were carried out in a Temperature Programmed Reaction system with toluene (1000 ppm) and synthetic air in the gas phase. It was observed that the oxidation of toluene starts at temperature as low as 280 °C and that Mn is responsible for most of the catalytic activity. However, the presence of small amounts of Fe (LaFe 0.27 Mn 0.73 O 3 ) leads to an increase in this activity. Stability studies showed that these perovskite catalysts are stable even after 100 h reaction at 400 o C with no significant structural change, as observed by XRD and Mössbauer analyses.Keywords: lanthanum iron perovskite, toluene oxidation, catalytic oxidation, manganese, molybdenum IntroductionPerovskite type oxides, ABO 3 , have been extensively investigated as catalysts for several processes including fuel cells, 1 water dissociation, 2 hydrogenation and hydrogenolysis, 3 ammonia oxidation 4 and NO x reduction. 5 Several reviews covering these fields can be found in the literature. 6,7 Perovskites, especially LaMnO 3 , have also been used in environmental applications, e.g. the oxidation of hydrocarbons, 8-10 chlorinated organics 11 and H 2 O 2 reactions. 6,12 LaMnO 3 shows good stability and flexible oxygen stoichiometry ( ) with different Mn oxidation states, i.e. Mn 2+ , Mn 3+ , Mn 4+ , which strongly affects the catalytic behavior. Also, the isomorphic substitution of metals in the perovskite structure allows a control of the catalytic properties of the material. Several LaMnO 3 1525 Tristão et a...

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Catalytic properties of stoichiometric and non-stoichiometric LaFeO3 perovskite for total oxidation of methane

Cited by 76 publications

References 8 publications

Surfactant-Assisted Perovskite Nanofillers Incorporated in Quaternized Poly (Vinyl Alcohol) Composite Membrane as an Effective Hydroxide-Conducting Electrolyte

Surfactant-Assisted Perovskite Nanofillers Incorporated in Quaternized Poly (Vinyl Alcohol) Composite Membrane as an Effective Hydroxide-Conducting Electrolyte

Controlled reduction of LaFe xMn yMo zO3/Al2O3 composites to produce highly dispersed and stable Fe0 catalysts: a Mössbauer investigation

LaFe xMn yMo zO 3 catalysts for the oxidation of volatile aromatic organic contaminants

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