Effect of Water on Methane and Ethane Oxidation in the Conditions of Oxidative Coupling of Methane Over Model Catalysts

Lomonosov, V. I.; Gordienko, Yu. A.; Sinev, M. Yu.

doi:10.1007/s11244-013-0122-2

Cited by 30 publications

(36 citation statements)

References 18 publications

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“…A positive effect of water on the rate of methane conversion over a similarly composed catalyst was previously reported by the groups of Iglesia , and Sinev . We also investigated the influence of water on HHV of the OCM product stream.…”

Section: Resultssupporting

confidence: 55%

“…A positive effect of water on the rate of methane conversion over a similarly composed catalyst was previously reported by the groups of Iglesia 16,17 and Sinev. 18 We also investigated the influence of water on HHV of the OCM product stream. As seen in Figure 5a, HHV augmented from 11.10 to 11.37 kW•h• m −3 as water concentration increased from 0 to 30 vol% and practically did not change with a further increase in the concentration.…”

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

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An Approach Using Oxidative Coupling of Methane for Converting Biogas and Acid Natural Gas into High-Calorific Fuels

Sokolov

Seeburg

Wohlrab

et al. 2018

Ind. Eng. Chem. Res.

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Biogas is a renewable resource with prospects in production of commodity chemicals or for power generation. The latter implies co-usage of biogas and natural gas in gas distribution nets but puts a restriction on the higher heating value (HHV) of all gases pumped into the net. In this contribution, we analyzed and experimentally validated the potential of the oxidative coupling of methane (OCM) as a method for upgrading biogas HHV. The effects of the reaction conditions, i.e., reaction temperature, feed CH 4 /O 2 ratio, and co-feeding of CO 2 or H 2 O, on HHV of the resulting gas mixtures were studied. The highest HHV of 11.48 kW•h•m −3 after water condensation was obtained when performing the OCM reaction over Mn− Na−WO x /SiO 2 catalyst at 800 °C using a feed with CH 4 /O 2 ratio of 12 and 30 vol% water. This performance was possible thanks to 86% selectivity to C 2 hydrocarbons (C 2 H 4 and C 2 H 6 ) at 15.2% methane conversion. It was also possible to increase the selectivity to 100% when carbon oxides formed in the OCM reaction were hydrogenated to methane in a separate reactor containing a Fe 2 O 3 catalyst and thus to obtain a gas mixture with HHV of 12.0 kW•h•m −3 . Such combined approach can open an environmentally friendly way for upgrading biogas or natural gas with high CO 2 content for direct applications in gas distribution nets when using green source of energy for H 2 O splitting to H 2 and O 2 required for the OCM and hydrogenation reactions, respectively.

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Section: Resultssupporting

confidence: 55%

Section: Industrial and Engineering Chemistry Researchmentioning

confidence: 99%

An Approach Using Oxidative Coupling of Methane for Converting Biogas and Acid Natural Gas into High-Calorific Fuels

Sokolov

Seeburg

Wohlrab

et al. 2018

Ind. Eng. Chem. Res.

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“…An alternative concept for the role of water in the OCM reaction over MnO x -Na 2 WO 4 /SiO 2 was introduced by Lomonosov et al 18 These authors assumed that water accelerates regeneration of catalytically active surface oxygen species. Importantly, the same group did not observe any water effect on the OCM reaction over La/MgO and PbO x /Al 2 O 3 tested under the same reaction conditions as MnO x -Na 2 WO 4 / SiO 2 .…”

Section: ■ Introductionmentioning

confidence: 99%

Revisiting Activity- and Selectivity-Enhancing Effects of Water in the Oxidative Coupling of Methane over MnO_x-Na₂WO₄/SiO₂and Proving for Other Materials

et al. 2020

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The oxidative coupling of methane (OCM) to C 2 -hydrocarbons (C 2 H 4 and C 2 H 6 ) is attractive both from fundamental (selective C−H bond activation) and applied viewpoints. The main drawback hindering its commercialization is the low selectivity to C 2 -hydrocarbons due to their further oxidation to carbon oxides. In this respect, we focused on elucidating fundamentals of the previously reported positive effect of water on the activity and selectivity in the OCM reaction over MnO x -Na 2 WO 4 /SiO 2 by means of steady-state kinetic and mechanistic tests at ambient pressure as well as temporal analysis of products with sub-millisecond resolution and isotopic tracers in vacuum. The obtained results cannot be rationalized by the earlier developed concepts explaining the role of water in the OCM reaction over this catalyst system. In addition, the selectivity-enhancing water effect was determined for MnO x

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“…19 Nevertheless, various other reasons for OCM selectivity improvement have been proposed to explain the effect induced by H 2 O. 25,26 O was caused by suppressing the formation of molecular surface oxygen species. 26 Aydin et al…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, various other reasons for OCM selectivity improvement have been proposed to explain the effect induced by H 2 O. , Sinev et al suggested that a low concentration of H 2 O facilitated the re-oxidation of active sites and thus improved the CH 4 conversion rate. The improved C 2 selectivity induced by H 2 O was caused by suppressing the formation of molecular surface oxygen species . Aydin et al proposed that water enhanced the CH 4 activation and CH 3 radical formation rate.…”

Section: Introductionmentioning

confidence: 99%

Transient Potassium Peroxide Species in Highly Selective Oxidative Coupling of Methane over an Unmolten K₂WO₄/SiO₂ Catalyst Revealed by In Situ Characterization

Yoshida

Siritanaratkul

et al. 2021

ACS Catal.

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The oxidative coupling of methane (OCM) over a K2WO4/SiO2 catalyst was investigated using a CH4–O2 flow system. The addition of H2O to the reactant stream caused an increase in the CH4 conversion rate and C2 selectivity, consistent with the kinetics associated with the equilibrated OH radical generation, followed by H-abstraction from CH4 with OH radicals. The C2+ (a sum of C2 and higher hydrocarbons) yield reaches a maximum of 24.7% (C2H4 yield 17.0%) at a CH4 conversion of 47.1%, comparable to those over the previously reported Na2WO4/SiO2 catalyst. In situ near ambient pressure X-ray photoelectron spectroscopy uncovered K2O2 and KO2 species at and above 560 °C in the presence of gas-phase O2. These K2O2/KO2 species are considered to catalyze H2O activation for OH radical generation. By in situ high-temperature X-ray diffraction, K2WO4 maintained a crystalline phase in the bulk during the OCM reaction at 850 °C in contrast to the molten state of Na2WO4 previously reported. This indicates that the melting of the supported component and the covering of support are not essential to achieve a high C2 yield in supported alkali metal tungstate catalysts as long as inert support materials are used toward OCM.

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Effect of Water on Methane and Ethane Oxidation in the Conditions of Oxidative Coupling of Methane Over Model Catalysts

Cited by 30 publications

References 18 publications

An Approach Using Oxidative Coupling of Methane for Converting Biogas and Acid Natural Gas into High-Calorific Fuels

An Approach Using Oxidative Coupling of Methane for Converting Biogas and Acid Natural Gas into High-Calorific Fuels

Revisiting Activity- and Selectivity-Enhancing Effects of Water in the Oxidative Coupling of Methane over MnO_x-Na₂WO₄/SiO₂and Proving for Other Materials

Transient Potassium Peroxide Species in Highly Selective Oxidative Coupling of Methane over an Unmolten K₂WO₄/SiO₂ Catalyst Revealed by In Situ Characterization

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Effect of Water on Methane and Ethane Oxidation in the Conditions of Oxidative Coupling of Methane Over Model Catalysts

Cited by 30 publications

References 18 publications

An Approach Using Oxidative Coupling of Methane for Converting Biogas and Acid Natural Gas into High-Calorific Fuels

An Approach Using Oxidative Coupling of Methane for Converting Biogas and Acid Natural Gas into High-Calorific Fuels

Revisiting Activity- and Selectivity-Enhancing Effects of Water in the Oxidative Coupling of Methane over MnOx-Na2WO4/SiO2and Proving for Other Materials

Transient Potassium Peroxide Species in Highly Selective Oxidative Coupling of Methane over an Unmolten K2WO4/SiO2 Catalyst Revealed by In Situ Characterization

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Product

Resources

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Revisiting Activity- and Selectivity-Enhancing Effects of Water in the Oxidative Coupling of Methane over MnO_x-Na₂WO₄/SiO₂and Proving for Other Materials

Transient Potassium Peroxide Species in Highly Selective Oxidative Coupling of Methane over an Unmolten K₂WO₄/SiO₂ Catalyst Revealed by In Situ Characterization