Catalytic combustion of methane over various perovskite-type oxides

Arai, Hiromichi; Yamada, Takuya; Eguchi, Koichi; Seiyama, Tetsuro

doi:10.1016/s0166-9834(00)82556-7

Cited by 492 publications

(220 citation statements)

References 11 publications

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“…Data show that LaMnO3 and LaCoO3 were the most active catalysts, while LaFeO3 was the less performing one, in spite of its higher lowtemperature activity through the suprafacial mechanism ( Fig.1), as previously observed [6,7,[16][17][18].…”

Section: -Effect Of the Nature Of B Metal On Activity And Resistance supporting

confidence: 79%

Effect of sulphur poisoning on perovskite catalysts prepared by flame-pyrolysis

Rossetti

Buchneva

Biffi

et al. 2009

Applied Catalysis B: Environmental

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ABO3 perovskite-like catalysts are known to be sensitive to sulphur-containing compounds. Possible solutions to increase resistance to sulphur are represented by either catalyst bed protection with basic guards or catalyst doping with different transition or noble metals. In the present work La(1-x)A'xCoO3, La(1-x)A'xMnO3 and La(1-x)A'xFeO3, with A' = Ce, Sr and x=0, 0.1, 0.2, either pure or doped with noble metals (0.5 wt% Pt or Pd), were prepared in nano-powder form by flame pyrolysis. All the catalysts were tested for the catalytic flameless combustion of methane, monitoring the activity by on-line mass spectrometry. The catalysts were then progressively deactivated in operando with a new procedure, consisting of repeated injection of some doses of tetrahydrothiophene (THT), usually employed as odorant in the natural gas grid, with continuous analysis of the transient response of the catalyst. The activity tests were then repeated on the poisoned catalyst. Different regenerative treatments were also tried, either in oxidising or reducing atmosphere.Among the unsubstituted samples, higher activity and better resistance to poisoning have been observed in general with manganites with respect to the corresponding formulations containing Co or Fe at the B-site. The worst catalyst showed LaFeO3, from both the points of view of activity and of resistance to sulphur * Corresponding author: fax +39-02-50314300, e-mail ilenia.rossetti@unimi.it 2 poisoning. La0,9Sr0,1MnO3 showed, the best results, exhibiting very high activity and good resistance even after the addition of up to 8.4 mg of THT per g of catalyst.Interesting results were attained also by adding Sr to Co-based perovskites. Sr showed a first action by forcing Mn or Co in their highest oxidation state, but, in addition, it could also act as a sulphur guard, likely forming stable sulphates due to its basicity. Among noble metals, Pt doping proved beneficial in improving the activity of both the fresh and the poisoned catalyst.Keywords: Methane, catalytic combustion; Sulphur poisoning; Perovskite-like catalysts. -INTRODUCTIONThe catalytic flameless combustion (CFC) of methane outperforms conventional flame combustion because of lower emission of pollutants (HC, CO and NOx) and high thermal efficiency. The catalysts traditionally used for CFC are mainly based on supported noble metals, such as Pd and Pt, which ensure high activity, however accompanied by some drawbacks, due to high cost and poor thermal and chemical stability. La-based catalysts with ABO3 perovskite-like structure [1][2][3][4] have been proposed as a valid alternative for the present application. Indeed, perovskite catalysts combine low cost, thermo-chemical stability at high operating temperature and satisfactory catalytic activity [5][6][7][8]. In spite of this, there are still some open questions, especially regarding their resistance to sulphur poisoning when used for the CFC of methane. Indeed, the poisoning mechanism of perovskite-like catalysts has not been completely understood a...

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Section: -Effect Of the Nature Of B Metal On Activity And Resistance supporting

confidence: 79%

Effect of sulphur poisoning on perovskite catalysts prepared by flame-pyrolysis

Rossetti

Buchneva

Biffi

et al. 2009

Applied Catalysis B: Environmental

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“…As expected, methane conversion increases with temperature with a sigmoidal profile. Indeed, depending the fixed temperature, different reaction pathway may controls the overall methane catalytic combustion [9,[28][29][30][31]. At low temperature, the combustion is controlled by the surface oxygen vacancies that are activate sites for oxygen adsorption.…”

Section: -6mentioning

confidence: 99%

“…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. Reaction rates were reported in the Arrhenius plot of fig.12 and the apparent activation energies, E a , for CH 4 disappearance were calculated from the slope of the interpolated data.…”

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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“…The development of a synthesis route capable of producing MgCr 2 O 4 nanomaterials with controlled size and morphology is important due to their potential applications as smart and functional materials. Various methods, such as solid state reaction (Finocchio et al 1995), sol-gel method (SG) (Andrade et al 2006), co-precipitation (Zhang et al 1987), solution combustion (Arai et al 1986), co-precipitation within reverse micro-emulsion (Rida et al 2010), combustion method (Hosterman et al 2013) and conventional double sintering ceramic technique (Khalaf et al 2016) have been applied in the preparation of pirochromite based nanoparticles. Nevertheless, some of these methods are generally complicated, non-reliable, timeconsuming, and expensive for large scale production.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of nanostructured pirochromite magnesium chromate with egg shell membrane template

Ramachandran

Hamed

2016

Appl Nanosci

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In this work, we report on the use of fresh and boiled egg shell membrane as bio-templates in the coprecipitation of pirochromite. The structure evolution, microstructure and optical properties of the ESM templated MgCr 2 O 4 nanomaterial were studied by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, Energy dispersive X-ray spectroscopy, elemental mapping and UV-Vis-NIR spectrophotometry. The annealing of the untemplated and templated co-precipitated MgCr 2 O 4 powders at 1000°C for 4 h produced single phased nanostructured material with spinel cubic crystal structure. The FTIR results showed slight variations in the band positions m 1 and m 2 which are attributed to the change in the microstructure due to the introduction of ESM in the preparation of MgCr 2 O 4 . The morphologies and average crystallite size of the annealed MgCr 2 O 4 nanocrystalline powders depended on the type of the template. 3D hierarchical flake-like and mesh like structures were observed. The annealed MgCr 2 O 4 nanocrystalline powders have shown excitonic absorptions in the visible range 300-500 nm due to the transitions that took place from the O-2p level to the Cr-3d level. The optical band gap energies were found to be 3.68-3.71 eV for the direct band gap and 3.30-3.37 eV for the indirect band gap. This could make these MgCr 2 O 4 nanocrystalline powders possible photocatalysts in the visible range 300-500 nm.

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Catalytic combustion of methane over various perovskite-type oxides

Cited by 492 publications

References 11 publications

Effect of sulphur poisoning on perovskite catalysts prepared by flame-pyrolysis

Effect of sulphur poisoning on perovskite catalysts prepared by flame-pyrolysis

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

Synthesis of nanostructured pirochromite magnesium chromate with egg shell membrane template

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