Effect of carbon dioxide on methane oxidative coupling kinetics

Smith, Kevin J.; Gałuszka, Jan

doi:10.1021/ie00025a003

Cited by 13 publications

(14 citation statements)

References 17 publications

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“…The inhibiting effect of CO 2 on the rate of the methane coupling was also reported for other catalysts, e.g. Li/MgO (Roos, 1989;Al-Zahrani et al, 1994), Li/Pb/CaO (Smith and Galuszka, 1994), MgO and Sm 2 O 3 with and without promoters, CaO, and SrO (Suzuki et al, 1990). In order to describe the inhibitory effect of various components on the rate of oxidation of hydrocarbons and the maximum in the dependence of the rate of ethane formation on partial pressure of oxygen Hougen-Watson type rate equation have been applied.…”

Section: Discussionsupporting

confidence: 72%

Comprehensive Kinetics of Oxidative Coupling of Methane over the La₂O₃/CaO Catalyst

Stansch

Mleczko

Baerns

1997

Ind. Eng. Chem. Res.

211

200

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A comprehensive 10-step kinetic model of the oxidative coupling of methane to C2+ hydrocarbons over a La2O3/CaO catalyst was developed on the basis of kinetic measurements in a microcatalytic fixed-bed reactor covering a wide range of reaction conditions (1 < p O 2 < 20 kPa, 10 < p CH 4 < 95 kPa, 700 < T < 955 °C, 0.76 m Cat/V̇ STP ≤ 250 kg·s/m3). The reaction scheme contains three primary and seven consecutive steps. The conversion of hydrocarbons and of carbon monoxide with oxygen were described by applying Hougen−Watson type rate equations. For the other reactions power-law rate equations were used. From the experimental data kinetic parameters, i.e. frequency factors, apparent activation energies, and adsorption enthalpies, were estimated. With the kinetic model the experimentally determined conversions of methane and oxygen, as well as yields to C2 hydrocarbons and carbon oxides, could be predicted with an average accuracy of ±20%.

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Section: Discussionsupporting

confidence: 72%

Comprehensive Kinetics of Oxidative Coupling of Methane over the La₂O₃/CaO Catalyst

Stansch

Mleczko

Baerns

1997

Ind. Eng. Chem. Res.

211

200

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“…Smith and Galuszka (1994) and AlZahrani et al (1994) modeled the effect of CO 2 addition using Hougen-Watson rate equations. In both papers the inhibiting effect of CO 2 addition was accounted for by a reaction similar to reaction 9.…”

Section: Simulation Resultsmentioning

confidence: 99%

Kinetics of a Gas-Phase Chain Reaction Catalyzed by a Solid: The Oxidative Coupling of Methane over Li/MgO-Based Catalysts

Couwenberg

Chen

Marin

1996

Ind. Eng. Chem. Res.

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A kinetic model was developed for the heterogeneously catalyzed oxidative coupling of methane for temperatures between 923 and 1023 K, inlet methane-to-oxygen ratios of 2 to 12, and oxygen conversions between 10 and 100%. This model features 10 catalytic reactions coupled to 39 gas-phase chain reactions and accounts for irreducible mass-transport limitations for reactive intermediates. The observed conversions and selectivities are adequately described up to 200 kPa total pressure. The observed strong increase of the conversions between 200 and 1000 kPa is described qualitatively. The catalyst not only produces radicals but also acts as an important radical quencher. Regeneration of the active sites through water desorption was found to be a kinetically significant step in the catalytic sequence producing methyl radicals. At atmospheric pressure approximately 90% of the methane and oxygen is converted on the surface of Sn/Li/MgO, the balance being converted through branched-chain reactions in the pores of the catalyst and in the interstitial phase. For Li/MgO only one-third of the methane is converted on the catalyst surface. For Sn/Li/MgO the catalytic oxidation of methyl radicals, rather than gas-phase reactions, limits the selectivity toward C2 products.

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“…Additionally, CO 2 can be used as an oxidant. In this way an active surface oxygen is supplied (needed for hydrogen abstraction from methane), without the generation of an additional gas phase oxygen resulting in even higher C 2 yields . Hydrocarbons, especially olefins, oxidize faster than methane leading back to CO 2 formation.…”

Section: Introductionmentioning

confidence: 99%

Non‐oxidative methane coupling to C₂ hydrocarbons in a microwave plasma reactor

Minea

Bekerom

Peeters

et al. 2018

Plasma Processes & Polymers

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Non‐oxidative methane activation is carried out in a microwave plasma reactor for coupling to higher hydrocarbons. Fourier transform infrared spectroscopy (FTIR) was used to measure absolute concentrations of the major hydrocarbon species. Hydrogen concentration was also independently inferred from pressure‐based change in molar flow measurements. By closing both the carbon and hydrogen balance, from stoichiometry of the reactions, the amount of deposits was obtained as well. Additionally, core gas temperatures up to 2500 K were measured with Raman scattering when nitrogen acted as probing molecule in sample mixture discharges. At low gas temperatures, ethane and ethylene were significant products based on plasma chemistry, with ethane selectivities reaching up to 60%. At higher gas temperatures, thermal effects become stronger shifting the selectivity toward acetylene and deposits, resembling more with equilibrium calculations. The energy efficiency of the methane conversion reached up to 15% from which 10% represented coupling efficiency to higher hydrocarbons. It is concluded that there is an interplay between plasma and thermal chemistry where plasma generates radicals and final distribution is set by thermodynamics.

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Effect of carbon dioxide on methane oxidative coupling kinetics

Cited by 13 publications

References 17 publications

Comprehensive Kinetics of Oxidative Coupling of Methane over the La₂O₃/CaO Catalyst

Comprehensive Kinetics of Oxidative Coupling of Methane over the La₂O₃/CaO Catalyst

Kinetics of a Gas-Phase Chain Reaction Catalyzed by a Solid: The Oxidative Coupling of Methane over Li/MgO-Based Catalysts

Non‐oxidative methane coupling to C₂ hydrocarbons in a microwave plasma reactor

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Effect of carbon dioxide on methane oxidative coupling kinetics

Cited by 13 publications

References 17 publications

Comprehensive Kinetics of Oxidative Coupling of Methane over the La2O3/CaO Catalyst

Comprehensive Kinetics of Oxidative Coupling of Methane over the La2O3/CaO Catalyst

Kinetics of a Gas-Phase Chain Reaction Catalyzed by a Solid: The Oxidative Coupling of Methane over Li/MgO-Based Catalysts

Non‐oxidative methane coupling to C2 hydrocarbons in a microwave plasma reactor

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Comprehensive Kinetics of Oxidative Coupling of Methane over the La₂O₃/CaO Catalyst

Comprehensive Kinetics of Oxidative Coupling of Methane over the La₂O₃/CaO Catalyst

Non‐oxidative methane coupling to C₂ hydrocarbons in a microwave plasma reactor