2009
DOI: 10.1007/s10562-009-9848-7
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On the La–Cr–O Phase Change During Methane Catalytic Combustion Investigated with in situ HT-XRD

Abstract: La 2 CrO 6 (Cr6), LaCrO 3 (Cr3), LaCrO 3 -La 2 CrO 6 (Cr6-Cr3) and LaCrO 3 -La 2 O 3 (Cr3-L) catalysts were synthesised and investigated with in situ X-ray diffraction (ISXRD) during methane catalytic combustion in order to characterise the solid phases present under reactants and to determine the effect of chromium oxidation state on the catalytic activity. Methane conversion was evaluated over a temperature range of 300-800°C, using oxygen-to-methane ratio of 4 and GHSV of 8,000 h -1 . The TPR provided infor… Show more

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Cited by 12 publications
(8 citation statements)
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“…2. TPR profile of the LaCrO 3 base perovskite does not show hydrogen consumption in agreement with the stability of Cr 3þ ions in the perovskite structure [14,31,32]. The LCrRu15 perovskite shows two H 2 -consumption peaks at 173 and 211 C. According to Aouad et al [33], the TPR profile of ruthenium oxide (IV) exhibits two reduction peaks at 101 and 142 C. Taking this fact into account and the segregation of ruthenium oxide species already observed by XRD (Fig.…”
Section: Temperature-programmed Reduction (Tpr)supporting
confidence: 73%
See 1 more Smart Citation
“…2. TPR profile of the LaCrO 3 base perovskite does not show hydrogen consumption in agreement with the stability of Cr 3þ ions in the perovskite structure [14,31,32]. The LCrRu15 perovskite shows two H 2 -consumption peaks at 173 and 211 C. According to Aouad et al [33], the TPR profile of ruthenium oxide (IV) exhibits two reduction peaks at 101 and 142 C. Taking this fact into account and the segregation of ruthenium oxide species already observed by XRD (Fig.…”
Section: Temperature-programmed Reduction (Tpr)supporting
confidence: 73%
“…5. Reflections belonging to the orthorhombic LaCrO 3 structure [14,36] are observed in all used catalysts. The well-defined perovskite structure is maintained after ATR reaction without segregation of phases in Sr-loaded used catalysts.…”
Section: X-ray Diffraction (Xrd)mentioning
confidence: 86%
“…In most of the literature studies, H 2 -TPR experiments carried out on LaCrO 3 do not provide consumption peaks below 900 • C since Cr(III)/Cr(II) reduction step requires higher temperatures [26,29]. Thus, our H 2 -TPR results, where LaCrO 3 exhibits a well defined Cr reduction peak, might be related to the reduction of a small amount of Cr(VI) in agreement with the XRD results, and to the contribution of Cr(IV) present in low concentration.…”
Section: Discussionmentioning
confidence: 99%
“…As a consequence, in these samples Cr(VI) should be taken into account for the reduction process [26,29]. The main reduction peak slightly shifts to lower temperature with increasing iron contents; moreover, a second broad and less intense peak appears between ∼600 • C and 850 • C (Fig.…”
Section: Reducibilitymentioning
confidence: 99%
“…1, 2 In terms of magnetic properties, the localized magnetic moments on Cr 3+ (3d 3 ) order antiferromagnetically below the Néel temperature (T N ) of 282 K, giving rise to a G x -type magnetic structure, with the Cr 3+ ions antiferromagnetically coupled to the six surrounding chromium ions. 3 Because of the anti-symmetric Dzyaloshinsky-Moriya interaction, this ordering is accompanied with the spin canting of the Cr 3+ moments.…”
Section: Introductionmentioning
confidence: 99%