Study of some aspects of the reactivity of La2O3 with CO2 and H2O

Bernal, S.; Díaz, José Antonio Acevedo; Garcı́a, R.; Rodrı́guez-Izquierdo, J.M.

doi:10.1007/bf01026524

Cited by 108 publications

(46 citation statements)

References 16 publications

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“…This is due to the formation of Ni particles during the time on stream. The calcined La 0.98 Sr 0.02 O x and Ni-containing catalysts (up to 10 mol.%) present lanthanum hydroxide as major crystalline phase, in line with the high tendency of lanthana to absorb carbon dioxide and water [20]. A minor mixed oxide phase was also observed in 10 mol.% Ni-containing catalyst.…”

Section: Resultsmentioning

confidence: 70%

“…The characterization of used La 2 O 3 -based catalysts by TG analysis can therefore provide important details about the role played by those molecules during the oxidative transformation of methane. According to previous reports [20,22], lanthana stabilized in air would consist of poorly crystallized It is therefore reasonable to expect the formation of hydroxycarbonate phases during the catalytic reaction, owing to the methane-oxygen interaction on the lanthana surface. Table 1 also shows the influence of the Ni loadings over the stoichiometric composition of the hydroxycarbonate phases.…”

Section: Resultsmentioning

confidence: 96%

“…Table 1 also shows the influence of the Ni loadings over the stoichiometric composition of the hydroxycarbonate phases. This ratio was determined using the weight losses associated with desorption of water and carbon dioxide upon the thermal treatment [20,23] …”

Section: Resultsmentioning

confidence: 99%

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Influence of lanthanum carbonate phases of Ni/La0.98Sr0.02O x catalyst over the oxidative transformation of methane

et al. 2006

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This work combines the advantages of $2 mol.% Sr/La 2 O 3 (i.e. La 0.98 Sr 0.02 O x ) for OCM (oxidative coupling of methane) with welldispersed nickel over metal oxides for POM (partial oxidation of methane) to efficiently transform methane to desirable products. The catalysts were prepared by sequential impregnation and characterized by X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, temperature-programmed reduction, temperature-programmed decomposition of carbonates and BET surface area measurements. The aim of this work is to find out not only the effect of the catalyst compositions over the formation and growth of carbonate phases, but also their influence over the transformation oxidative of methane.The La 0.98 Sr 0.02 O x -supported Ni catalyst precursors show a strong nickel oxide-lanthana interaction, involving anionic vacancies or structural defects that induce the formation of island-like structure of La 2-x Sr x NiO 4 -type mixed oxide for 2 mol.% Ni/La 0.98 Sr 0.02 O x . Higher nickel composition facilitates the formation of LaNiO 3 . Surface lanthanum hydroxycarbonate formation is probably associated with a conjugated effect between lanthanum oxide and oxidized nickel phases. For high-nickel amount containing catalysts, carbonate-enriched La 2 (OH) 6-2x (CO 3 ) x as intermediate phase in methane reforming reaction is proposed. For low nickel composition (i.e. 2%), partial oxidation of methane could follow predominantly the pyrolysis mechanism. In which, carbon monoxide is the direct product and carbon dioxide is subsequently formed from carbon monoxide oxidation.

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Section: Resultsmentioning

confidence: 70%

Section: Resultsmentioning

confidence: 96%

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Influence of lanthanum carbonate phases of Ni/La0.98Sr0.02O x catalyst over the oxidative transformation of methane

et al. 2006

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“…When La 2 O 3 is in contact with ambient air, it rapidly forms La(OH) 3 . According to previous literature reports [17,22,23], the aging of La(OH) 3 in air at room temperature (RT) results in the formation of partially hydrated carbonates of La (OH) (CO 3 ) type. In [17], the aging of La(OH) 3 material at RT in ambient air was followed by annealing at 400 ∘ C, and, as a result, the sample was crystallized into pure hexagonal La 2 O 2 CO 3 phase.…”

Section: Resultsmentioning

confidence: 99%

Structure-Dependent CO₂ Gas Sensitivity of La₂O₂CO₃ Thin Films

et al. 2017

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Rare earth oxycarbonates are potential candidate materials for constructing simple and low-cost chemiresistive sensors for monitoring carbon dioxide (CO 2 ) gas in the living and working environment for personal comfort and health reasons. Also, measurement of CO 2 concentrations is needed in many industrial processes. Specifically, sol-gel made nanoparticles of Nd and La oxycarbonates have been studied previously as novel CO 2 gas sensor materials. In this paper, pulsed laser deposition of La oxycarbonate (La 2 O 2 CO 3 ) thin films was studied and structural properties of obtained thin films were characterized. Also, CO 2 gas sensing ability of synthesized films was evaluated. The films deposited under CO 2 partial pressure in various conditions were all Raman amorphous. In situ or ex situ annealing procedure at high CO 2 partial pressure was needed for obtaining crystalline La 2 O 2 CO 3 films, whereby hexagonal and monoclinic polymorphs were obtained in ex situ and in situ processes, respectively. Sensor structure, made using in situ process, was sensitive to CO 2 gas and showed relatively fast response and recovery characteristics.

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“…Lanthana, because of its basic character, strongly reacts with H 2 O and CO 2 . When La 2 O 3 is stabilized in air (exposed to atmospheric CO 2 and H 2 O), hydration and carbonation processes easily occur leading to the formation of hydrated phase (La 2 O 3 -H 2 O), carbonated phase (La 2 O 3 -CO 2 ) and hydrated-carbonate phase (La 2 O 3 -CO 2 -H 2 O) [18]: the hydroxycarbonate species [20] result to be a thermodynamically stable phase.…”

Section: Methodsmentioning

confidence: 99%

Promotion effect of surface Lanthanum in soot oxidation over ceria-based catalysts

et al. 2007

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In the present work the soot combustion activity of CeO 2 doped with lanthanum hydroxide, as surface promoter, has been investigated. TGA experiments, run under different conditions, show that, in the presence of lanthana, the reaction of soot starts at low temperature (579 K) due to the possibility to form carbonate species. The emission of CO 2 is delayed due to the strong interaction with lanthana. A mechanism of reaction involving a carbonate route is proposed.

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Study of some aspects of the reactivity of La2O3 with CO2 and H2O

Cited by 108 publications

References 16 publications

Influence of lanthanum carbonate phases of Ni/La0.98Sr0.02O x catalyst over the oxidative transformation of methane

Influence of lanthanum carbonate phases of Ni/La0.98Sr0.02O x catalyst over the oxidative transformation of methane

Structure-Dependent CO₂ Gas Sensitivity of La₂O₂CO₃ Thin Films

Promotion effect of surface Lanthanum in soot oxidation over ceria-based catalysts

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Study of some aspects of the reactivity of La2O3 with CO2 and H2O

Cited by 108 publications

References 16 publications

Influence of lanthanum carbonate phases of Ni/La0.98Sr0.02O x catalyst over the oxidative transformation of methane

Influence of lanthanum carbonate phases of Ni/La0.98Sr0.02O x catalyst over the oxidative transformation of methane

Structure-Dependent CO2 Gas Sensitivity of La2O2CO3 Thin Films

Promotion effect of surface Lanthanum in soot oxidation over ceria-based catalysts

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Structure-Dependent CO₂ Gas Sensitivity of La₂O₂CO₃ Thin Films