Óxidos do tipo perovskita para reação de redução de no com CO

Tanabe, Eurico Yuji; Assaf, Elisabete Moreira

doi:10.1590/s0100-40422009000500009

Cited by 15 publications

(13 citation statements)

References 7 publications

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“…The strontium accommodation in the structure of lanthanum nickel is more difficult than the same substitution in other similar perovskites [5]. This same observation was related, for example, in solid solutions of La-Sr-Mn-O without the presence of segregated crystalline phase [7]. However, segregated phases of oxides and carbonates were observed for the compositions with molar amounts of Sr 2+ greater than 0.10 and an increase in the oxygen non-stoichiometry with increasing strontium.…”

Section: Wavenumber (Cm -1 )mentioning

confidence: 90%

“…However, segregated phases of oxides and carbonates were observed for the compositions with molar amounts of Sr 2+ greater than 0.10 and an increase in the oxygen non-stoichiometry with increasing strontium. However, it was observed an increase in the catalytic activity of the catalysts when doped with strontium [5,7]. Lanthanum (La ) being compensated by the oxygen deficiency (vacancies) [5], which can generate an improvement in the catalytic activity.…”

Section: Wavenumber (Cm -1 )mentioning

confidence: 99%

“…It is possible to carry out partial substitutions of cations A and B without changing the fundamental structure of the perovskite [4]. The effect of the partial replacement of the cation A, usually by a rare earth metal, and especially with elements with oxidation state other than +3, has been frequently studied [5][6][7]. However, interest in perovskite studies is promising in applications involving high temperatures due to their high stability.…”

Section: Introductionmentioning

confidence: 99%

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Nickel-based perovskite catalysts: synthesis and catalytic tests in the production of syngas

et al. 2018

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La 1-x Sr x NiO 3 (x= 0.0, 0.3 or 0.7) perovskite-type oxides were synthesized using the modified proteic gel method and using collagen as an organic precursor. Catalysts of La 1-x Sr x NiO 3 /Al 2 O 3 were obtained using the wet impregnation method. The synthesized catalysts were characterized by X-ray diffraction, surface area and temperature-programmed reduction. The catalysts were evaluated in the partial oxidation reaction of methane, and the levels of selectivity to CO, CO 2 , H 2 and H 2 O were determined. Among the catalysts studied, the catalyst LaNiO 3 /Al 2 O 3 had the highest methane conversion level (78%) and higher H 2 selectivity (55%). Keywords: La 1-x Sr x NiO 3 , perovskite-type oxides, modified proteic gel method, partial oxidation of methane. Resumo Perovskitas do tipo

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Section: Wavenumber (Cm -1 )mentioning

confidence: 90%

Section: Wavenumber (Cm -1 )mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nickel-based perovskite catalysts: synthesis and catalytic tests in the production of syngas

et al. 2018

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“…However, we will be more specific in our work, since here we studied the Fe 4 O oxide, because these materials have a well-defined structure, the perovskite. Some recent experimental papers written by brazilian authors 11 explain about the structure of perovskite oxides, but leave poor research using quantum models that give us information about the properties of the ground state of oxides. In this article, the electronic structure is solved, obtained the ground state properties of the Fe 4 O, oxide and its comparison with some results obtained from γ -Fe 4 N, which also has the same perovskite structure.…”

Section: Introduction and Literature Reviewmentioning

confidence: 99%

Pressure Influence on the Stability and Formation of γ - Fe4N when Transformed into Fe4O

Santos

Costa

2013

Mat. Res.

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The improved technology has allowed the study of electronic structure of solids with a complex crystalline structure and containing various atoms, different in the unit cell, and thus we can calculate the energy of formation and obtaining the bulk modulus and cohesive energy, which lets us discussing the compounds stability. The importance of this work is to obtain the ground state properties of solids face the crystal lattice deformation when subjected to pressure. The nitrogen replacement by oxygen in the interstitial structure γ -Fe 4 N forming Fe 4 O was studied. Calculations indicate that the critical pressure to transform the ferromagnetic into non-magnetic phase is greater in the γ -Fe 4 N 528,8851 Kbar showing a greater magnetic character. Regarding the resistance to uniform compression (bulk modulus), our calculations show that γ -Fe 4 N is higher, because a bulk modulus of 281.4045 GPa for non-magnetic phase and 173.7893 GPa for Fe 4 O 251.3927 GPa for non-magnetic and 170.1810 GPa for ferromagnetic, showing that the non-magnetic phase have higher bulk modulus for both compounds.

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“…La mayoría de las síntesis industriales de polvos para aplicación en cerámicas se obtiene por medio del método cerámico tradicional o reacción en estado sólido, también llamada de mezcla de óxidos (Yang et al, 2003;Ikeguche et al, 2005;Casanova et al, 2004;Liu et al, 2000;Teraoka et al, 2002). Entre los varios métodos de síntesis encontrados en la literatura, podemos citar: evaporation by dryness (Teraoka et al, 1988;Yaremchenlo y Kharton, 1999), método Pechini (Waller et al, 1996;), sol-gel (Vargas et al, 2007), técnicas de los citratos (Shao et al, 2000;Dong et al, 2001;Tong et al, 2002), creación de complejo combinando EDTA-citrato (Shao et al, 2001;Ikeguchi et al, 2003;2005;, co-precipitación (Oliveira et al;Rivas et al, 2008;Ouaguenouni et al, 2009;Tanabe Y Assaf, 2009). …”

Section: Introductionunclassified

Síntesis y Refinado por el Método Rietveld de la fase perovsquita obtenida a partir del Método de Co-precipitación vía Oxalato

et al. 2011

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ResumenMaterial cerámico del tipo perovisquita SrCo 0,8 Fe 0,2 O 3-δ fue sintetizado usando el método de coprecipitación en medio oxalato. Durante los análisis térmico-gravimétrico y térmico-diferencial (TG/DTA) se verificó que independientemente de la naturaleza del reactivo o agente precipitante adoptado en la síntesis del precursor, la curva termogravimétrica presenta tres etapas, con pérdida de masa total de aproximadamente el 40 %. Mediante difracción de rayos X se verificó que el tamaño medio del cristalito fue de aproximadamente 77,22 nm utilizando nitrato de Hierro III, casi un 83 % superior al obtenido usando oxalato de Hierro III (42,23 nm). Sin embargo, la variación del agente precipitante no afectó prácticamente al tamaño mediano de cristalino (42,95 nm y 42,23 nm). El material presenta isotermas de tipo II, con una superficie específica de aproximadamente 4,41m 2 g -1 . Palabras clave: perovsquita, método co-precipitación, oxalato, refinamiento Rietveld Synthesis and Refining by Rietveld Method of the perovskite phase obtained using Oxalate Coprecipitation Method AbstractPowders of perovskite SrCo 0.8 Fe 0.2 O 3-δ were synthesized using oxalate co-precipitation method. According to the thermal gravimetry and differential thermal analysis (TG/DTA), total mass loss was 40 % corresponding to three different steps and the precipitant agent as well the starting chemical elements have no influence on the process. Perovskite phase was identified by x-ray diffraction and the average crystallite size was 77.22 nm using iron nitrate (III) as starting material while 42.23 nm were obtained using iron oxalate (III). Ammonium oxalate and equimolar mixtures of ammonium oxalate and oxalic acid were used as precipitant agents and the results shown that these reactants have no influence on the average crystallite size (42.95 nm and 42.23 nm). The material presents isotherms of type II, with especific surface of approximately 4,41m 2 g -1 .

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Óxidos do tipo perovskita para reação de redução de no com CO

Cited by 15 publications

References 7 publications

Nickel-based perovskite catalysts: synthesis and catalytic tests in the production of syngas

Nickel-based perovskite catalysts: synthesis and catalytic tests in the production of syngas

Pressure Influence on the Stability and Formation of γ - Fe4N when Transformed into Fe4O

Síntesis y Refinado por el Método Rietveld de la fase perovsquita obtenida a partir del Método de Co-precipitación vía Oxalato

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