A kinetic model for the oxidative coupling of methane over Na2WO4/Mn/SiO2

Lee, Mi Ran; Park, Myung-June; Jeon, Wonjin; Choi, Ji‐Won; Suh, Young‐Woong; Suh, Dong Jin

doi:10.1016/j.fuproc.2011.12.038

Cited by 67 publications

(28 citation statements)

References 42 publications

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“…In particular, it has been determined that the selectivity has increased 2–3 times. It is known that increasing GHSV generally decreases methane conversion but increases C 2 selectivity [22–24] . When the oxygen conversions were investigated it was observed that at lower space velocity the conversions were not complete even at 600 °C but they were complete at higher space velocity.…”

Section: Resultsmentioning

confidence: 97%

“…It is known that increasing GHSV generally decreases methane conversion but increases C 2 selectivity. [22][23][24] When the oxygen conversions were investigated it was observed that at lower space velocity the conversions were not complete even at 600°C but they were complete at higher space velocity. Thus, at a lower GHSV value, mass transfer limitation for oxygen caused a decrease in methane conversion and in turn lowered the activity and selectivity.…”

Section: Resultsmentioning

confidence: 99%

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Detailed Investigation of Sm₂O₃ Catalysts with Different Morphologies for Oxidative Coupling of Methane

Özdemi̇r

2021

ChemistrySelect

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Sm 2 O 3 catalysts with different morphologies (nanoparticle, nanorod, hollow nanosphere, nanofiber, flower-like) were synthesized and tested for the oxidative coupling of methane. The results obtained showed that increasing specific surface area reduced the activity, C 2 selectivity and, thus the yield. It was observed that the reaction initiation temperature was dependent on the total or partial oxidation of methane, which produced the heat for the initiation of the reaction. The effect of temperature on catalytic performance was relatively low at lower temperatures (< 600°C) than at higher temperatures (> 700°C). High reaction temperatures (> 700°C) decreased the C 2 selectivity, lower temperatures were found beneficial to achieve higher C 2 selectivity and yield as expected. Hollow nanosphere morphology showed the highest activity and selectivity at 450°C and yielded 10.5 % C 2 under high space velocity. The highest C 2 yield (11.8 %) was obtained at 600°C with nanoparticle morphology. Considering the results at the conditions that full oxygen conversion was attained, it was found that the C 2 selectivity and yield decreased with the nanoparticle > flower-like > nanorod and nanosphere > nanofiber sequence.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Detailed Investigation of Sm₂O₃ Catalysts with Different Morphologies for Oxidative Coupling of Methane

Özdemi̇r

2021

ChemistrySelect

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“…39 Diluting the reactant mixture decreases the partial pressures of methane and O 2 and thus improves the selectivity for coupled C 2+ hydrocarbons while suppressing the formation of CO and CO 2 . 39,44,45 This change in the OCM results was more signicant at the higher temperatures of 800-850 C (with CH 4 conversions > 20%) and less signicant at 750 C (with CH 4 conversions < 20%). When the feed was highly diluted at the low reaction temperature, the formed methyl radicals may not be able to undergo gas-phase coupling with other methyl radicals in the highly diluted environment, which may reduce the C 2+ selectivity.…”

Section: Catalytic Activity Measurementmentioning

confidence: 93%

Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O₂, surface lattice oxygen, and CO₂ on the C₂₊ selectivity

et al. 2020

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“…Although OCM can increase biogas fuel quality, the presence of H 2 S in the raw biogas feed results in significant catalyst poisoning. OCM involves three steps, namely (i) the activation of CH 4 by O 2 species adsorbed on the catalyst surface to prepare CH 3 · radicals, (ii) gas‐phase coupling of CH 3 ·radicals to form paraffins, and (iii) dehydrogenation of C 2+ paraffins to olefins 20–26 . Steps (i) and (iii) are confined to the catalyst surface and may involve the binding of sulfur (S) species to catalytically active sites, which suppresses the formation of CH 3 · radicals and olefins.…”

Section: Introductionmentioning

confidence: 99%

Upgrading of sulfur‐containing biogas into high quality fuel via oxidative coupling of methane

Choi

Suh

et al. 2021

Int J Energy Res

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Summary Biogas, which contains methane (CH4), carbon dioxide (CO2), hydrogen sulfide (H2S), and other minor compounds, is a promising energy source and chemical feedstock (not least because it is generated from waste); however, its application as fuel is limited because of its low calorific value, which can be mitigated by upgrading biogas to high‐quality fuels via the oxidative coupling of methane (OCM), a catalytic process that increases its higher heating value from 39.9 (CH4, Wobbe index = 53.5 MJ/Nm3) to 41.7 MJ/Nm3 (OCM product mixture, Wobbe index = 54.4 MJ/Nm3), thus achieving compliance with the fuel standards in many countries (Wobbe index = 45.5‐55.0 MJ/Nm3). Among the compounds produced during OCM, H2S is formed in minor amounts but strongly suppresses biogas valorization, mainly because of potential catalyst poisoning. To understand the effects of sulfur compounds on OCM catalysts, three such catalysts, namely perovskites (SrTiO3 and LaAlO3) and Na2WO4/Mn/SiO2 (NWM), were used to convert biogas into olefins and paraffins. The oxidation of H2S in biogas produced sulfur dioxide, which did not strongly affect NWM but was strongly adsorbed by perovskites and, in turn, significantly reduced their OCM activity. Furthermore, long‐term (100 hours) stability testing demonstrated that the OCM activity of NWM was stable in the presence of H2S. Consequently, the influence of sulfur compounds on the catalysts during the OCM process was elucidated, including catalyst poisoning via sulfur species adsorption. The strategy to suppress the detrimental effects of sulfur poisoning was suggested, which can contribute to the development of feasible process for valorizing biogas to high quality fuels and chemicals.

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A kinetic model for the oxidative coupling of methane over Na2WO4/Mn/SiO2

Cited by 67 publications

References 42 publications

Detailed Investigation of Sm₂O₃ Catalysts with Different Morphologies for Oxidative Coupling of Methane

Detailed Investigation of Sm₂O₃ Catalysts with Different Morphologies for Oxidative Coupling of Methane

Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O₂, surface lattice oxygen, and CO₂ on the C₂₊ selectivity

Upgrading of sulfur‐containing biogas into high quality fuel via oxidative coupling of methane

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A kinetic model for the oxidative coupling of methane over Na2WO4/Mn/SiO2

Cited by 67 publications

References 42 publications

Detailed Investigation of Sm2O3 Catalysts with Different Morphologies for Oxidative Coupling of Methane

Detailed Investigation of Sm2O3 Catalysts with Different Morphologies for Oxidative Coupling of Methane

Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O2, surface lattice oxygen, and CO2 on the C2+ selectivity

Upgrading of sulfur‐containing biogas into high quality fuel via oxidative coupling of methane

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Product

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Detailed Investigation of Sm₂O₃ Catalysts with Different Morphologies for Oxidative Coupling of Methane

Detailed Investigation of Sm₂O₃ Catalysts with Different Morphologies for Oxidative Coupling of Methane

Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O₂, surface lattice oxygen, and CO₂ on the C₂₊ selectivity