Pretreatment effects on the active site for methane activation in the oxidative coupling of methane over MgO and Li/MgO

1995 ◽  
Vol 35 (1-2) ◽  
pp. 23-32 ◽  
Author(s):  
Kent Coulter ◽  
Janos Szanyi ◽  
D. Wayne Goodman
Keyword(s):  
Active Site ◽  
Oxidative Coupling ◽  
Oxidative Coupling Of Methane ◽  
Methane Activation ◽  
Pretreatment Effects

Effect of Mg substitution on LaTi1−xMgxO3+δ catalysts for improving the C2 selectivity of the oxidative coupling of methane

2021 ◽  
Author(s):  
Larissa B. Lopes ◽  
Luiz H. Vieira ◽  
José M. Assaf ◽  
Elisabete M. Assaf
Keyword(s):  
Active Site ◽  
Oxidative Coupling ◽  
Oxidative Coupling Of Methane ◽  
Site Distribution ◽  
Surface Active ◽  
Mg Substitution

Mg substitution on B sites of La2Ti2O7 perovskites promoted changes in the surface active-site distribution leading to improvements in the C2 selectivity during the oxidative coupling of methane.

On the active site of MgO/CaO mixed oxide for oxidative coupling of methane

1992 ◽  
Vol 134 (2) ◽  
pp. 422-433 ◽  
Author(s):  
R. Philipp ◽  
K. Omata ◽  
A. Aoki ◽  
K. Fujimoto
Keyword(s):  
Mixed Oxide ◽  
Active Site ◽  
Oxidative Coupling ◽  
Oxidative Coupling Of Methane

scholarly journals “Soft” oxidative coupling of methane to ethylene: Mechanistic insights from combined experiment and theory

2021 ◽  
Vol 118 (23) ◽  
pp. e2012666118
Author(s):  
Shanfu Liu ◽  
Sagar Udyavara ◽  
Chi Zhang ◽  
Matthias Peter ◽  
Tracy L. Lohr ◽  
...  
Keyword(s):  
Oxidative Coupling ◽  
Methane Conversion ◽  
Density Functional ◽  
Activation Barrier ◽  
Oxidative Coupling Of Methane ◽  
Methane Activation ◽  
Kinetic Isotope ◽  
Mechanistic Analysis ◽  
Adsorbed Sulfur ◽  
Product Forms

The oxidative coupling of methane to ethylene using gaseous disulfur (2CH4 + S2 → C2H4 + 2H2S) as an oxidant (SOCM) proceeds with promising selectivity. Here, we report detailed experimental and theoretical studies that examine the mechanism for the conversion of CH4 to C2H4 over an Fe3O4-derived FeS2 catalyst achieving a promising ethylene selectivity of 33%. We compare and contrast these results with those for the highly exothermic oxidative coupling of methane (OCM) using O2 (2CH4 + O2 → C2H4 + 2H2O). SOCM kinetic/mechanistic analysis, along with density functional theory results, indicate that ethylene is produced as a primary product of methane activation, proceeding predominantly via CH2 coupling over dimeric S–S moieties that bridge Fe surface sites, and to a lesser degree, on heavily sulfided mononuclear sites. In contrast to and unlike OCM, the overoxidized CS2 by-product forms predominantly via CH4 oxidation, rather than from C2 products, through a series of C–H activation and S-addition steps at adsorbed sulfur sites on the FeS2 surface. The experimental rates for methane conversion are first order in both CH4 and S2, consistent with the involvement of two S sites in the rate-determining methane C–H activation step, with a CD4/CH4 kinetic isotope effect of 1.78. The experimental apparent activation energy for methane conversion is 66 ± 8 kJ/mol, significantly lower than for CH4 oxidative coupling with O2. The computed methane activation barrier, rate orders, and kinetic isotope values are consistent with experiment. All evidence indicates that SOCM proceeds via a very different pathway than that of OCM.

ChemInform Abstract: On the Active Site of MgO/CaO Mixed Oxide for Oxidative Coupling of Methane.

ChemInform ◽  
2010 ◽  
Vol 23 (28) ◽  
pp. no-no
Author(s):  
R. PHILIPP ◽  
K. OMATA ◽  
A. AOKI ◽  
K. FUJIMOTO
Keyword(s):  
Mixed Oxide ◽  
Active Site ◽  
Oxidative Coupling ◽  
Oxidative Coupling Of Methane

Online Kinetics Study of Oxidative Coupling of Methane over La2O3 for Methane Activation: What Is Behind the Distinguished Light-off Temperatures?

ACS Catalysis ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 11761-11772 ◽  
Author(s):  
Zebang Liu ◽  
Jerry Pui Ho Li ◽  
Evgeny Vovk ◽  
Yan Zhu ◽  
Shenggang Li ◽  
...  
Keyword(s):  
Oxidative Coupling ◽  
Oxidative Coupling Of Methane ◽  
Methane Activation ◽  
Kinetics Study
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