Oxidative dimerization of methane over lanthanum oxide

Lin, Chih‐Yuan; Campbell, Karlyn Kohrs; Wang, Ji‐Xiang; Lunsford, Jack H.

doi:10.1021/j100276a004

Cited by 255 publications

(77 citation statements)

References 1 publication

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“…N 2 O or O 2 [3], etc). Under many circumstances, the superoxide O 2 -species has also been observed [12][13][14][15]. In our view, however, the role of O 2 -has been downplayed or even unfortunately ignored [16,17].…”

Section: Introductionmentioning

confidence: 62%

“…7 [13,14]. They claimed that no O -and O 3 -were detectable even when Li + was added to La 2 O 3 as done in the Li/MgO system [13].…”

Section: Epr Characterizationmentioning

confidence: 99%

“…They claimed that no O -and O 3 -were detectable even when Li + was added to La 2 O 3 as done in the Li/MgO system [13]. They suggested that O 2 -can activate a methane molecule, but provided the other alternative that a transient O -species may indeed be formed via O 2 -, and, in the presence of CH 4 , may give rise to the CH 3 radicals [14]. A similar explanation may be applicable to our system.…”

Section: Epr Characterizationmentioning

confidence: 99%

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Isotopic Oxygen Exchange and EPR Studies of Superoxide Species on the SrF2/La2O3 Catalyst

Wang

Weng

et al. 2007

Catal Lett

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By using the in situ IR spectroscopy, the superoxide species (O 2 -), characterized by the O-O stretching peak at 1130 cm -1 , was detected on the SrF 2 / La 2 O 3 catalyst at temperatures up to 973 K. The introduction of 18 O 2 isotope caused the 1130 cm -1 peak to shift to lower wavenumbers (1095 and 1064 cm -1 ), consistent with the assignment of the spectra to the superoxide species. A good correlation between the rate of the disappearance of the O 2 -species and that of the formation of C 2 H 4 was observed, suggesting that O 2 -was the active oxygen species responsible for the oxidative coupling of methane (OCM) on the SrF 2 /La 2 O 3 catalyst. This conclusion was reinforced by the EPR experiments (g xx = 2.0001, g yy = 2.0045, g zz = 2.0685), showing that O 2 -was the only paramagnetic oxygen species detectable on the O 2 -preadsorbed SrF 2 /La 2 O 3 catalyst. These results suggest that superoxide O 2 -can be a stable active oxygen species, whose role in the OCM reaction cannot be overlooked.

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Section: Introductionmentioning

confidence: 62%

“…7 [13,14]. They claimed that no O -and O 3 -were detectable even when Li + was added to La 2 O 3 as done in the Li/MgO system [13].…”

Section: Epr Characterizationmentioning

confidence: 99%

Section: Epr Characterizationmentioning

confidence: 99%

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Isotopic Oxygen Exchange and EPR Studies of Superoxide Species on the SrF2/La2O3 Catalyst

Wang

Weng

et al. 2007

Catal Lett

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“…The Li + O − centers are formed by the substitution of Li for Mg in the MgO lattice which is possible since the respective ionic radii of Li + and Mg 2 + are nearly equivalent. Besides O − anions also other reactive forms of oxygen were mentioned in the oxidative coupling of methane, e.g., the superoxide anion O − 2 (11,12), the oxide anion O 2− (13)(14)(15), the peroxide anion O 2− 2 (16)(17)(18)(19), and the ozonide anion O − 3 (11). The oxidative coupling over MgO and Li/MgO (20)(21)(22) and Sn/Li/MgO (22) was studied using steady-state isotopic transient kinetic analysis.…”

Section: Introductionmentioning

confidence: 99%

An Investigation of the Oxygen Pathways in the Oxidative Coupling of Methane over MgO-Based Catalysts

Mallens

Hoebink

Marin

1996

Journal of Catalysis

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The oxidative coupling of methane to ethane and ethene has been investigated by admitting pulses of pure methane, pure oxygen, and mixtures of methane and oxygen to MgO, Li/MgO, and Sn/Li/MgO at temperatures ranging from 923 to 1073 K in a Temporal Analysis of Products (TAP) set-up. Moreover, pulses of oxygen followed by pulses of either methane, ethane, ethene, or carbon monoxide were applied to study the role of both adsorbed oxygen and surface lattice oxygen in the reaction mechanism.

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“…The latter is It is worth noting that ethylene adsorbs irreversibly on clear platinum with dissociation into an acetylenic species and mobile hydrogen [67].…”

mentioning

confidence: 99%

Surface Species Formed during Methane Oxidation over Some Rare Earth Elements Oxides

Al-Dosari¹

2018

GSC

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This study has compared the ability of paramagnetic element oxides i.e. Pr, Eu, Yb in catalyst oxidation of methane. These have been prepared by precipitation, and then calcined at 600˚C to get M 2 O 3 . Methane was then passed through a disk in KBr, and the reactions were conducted at room temperature; 200˚C and then 300˚C. The reaction products were then identified by F.T.I.R spectroscopy. It was observed that these oxides have extracted the protons from methane and the CH 3• radicals were evidently formed. This focused radical react further to give CH 3 O, C 2 H 6 and the formation of Propionic acid is reported as one of the catalytic reaction products. The study also indicated the presence of aromatic products and in some instances, phenol was identified. Thereafter, the mechanism of the reaction was envisaged. For all the catalysts the conversion increases relatively with increasing the reaction temperature. The study can deduce that these oxides have the same ability as those of high paramagnetic properties to extract the proton, but the products are trapped and react further on the surface of the oxide.

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Oxidative dimerization of methane over lanthanum oxide

Cited by 255 publications

References 1 publication

Isotopic Oxygen Exchange and EPR Studies of Superoxide Species on the SrF2/La2O3 Catalyst

Isotopic Oxygen Exchange and EPR Studies of Superoxide Species on the SrF2/La2O3 Catalyst

An Investigation of the Oxygen Pathways in the Oxidative Coupling of Methane over MgO-Based Catalysts

Surface Species Formed during Methane Oxidation over Some Rare Earth Elements Oxides

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