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Oxidative coupling of methane: catalytic behaviour assessment via comprehensive microkinetic modelling

Paper ID Volume ID Publish Year Pages File Format Full-Text
45957 46427 2014 10 PDF Available
Title
Oxidative coupling of methane: catalytic behaviour assessment via comprehensive microkinetic modelling
Abstract

•Comprehensive one-dimensional heterogeneous microkinetic model for methane oxidative coupling.•Active sites density, oxygen, and hydroxyl chemisorption heat determine the catalyst activity.•C2 selectivity is mainly determined by oxygen chemisorption heat and CH3 sticking coefficient.•Performance of SrLaO and (Sn)LiMgO was assessed using a single microkinetic model.

A comprehensive microkinetic model, including catalyst descriptors, that accounts for thermal, homogeneous and catalytic, heterogeneous reaction steps in the oxidative coupling of methane has been used in the assessment of kinetic data acquired on different catalysts. The applicability of the model was extended from alkali magnesia catalysts represented by Li/MgO and Sn–Li/MgO, to a new class of materials, namely alkaline earth-promoted lanthana catalysts, represented by Sr/La2O3. To simulate adequately the large experimental dataset, acquired with the latter catalyst, the surface reaction network of the microkinetic model was expanded. The resulting model succeeded in adequately simulating the C2, that is, ethane and ethene, production, both individually and as a lump during regression. It was found that the activity of Sr/La2O3, in terms of methane conversion, is 33 and five times higher than that of Li/MgO and Sn–Li/MgO, respectively. This is attributed mainly to the higher stability of adsorbed hydroxyl, the higher stability of adsorbed oxygen, and the higher active density of Sr/La2O3. The selectivity toward C2 products was found to depend on the methyl radical sticking coefficient and the stability of the adsorbed oxygen and was the highest on the Sn-promoted LiMgO catalyst, that is, 70% at about 5% methane conversion at 1023 K, 190 kPa, and inlet molar CH4/O2 ratio of 4.

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Keywords
Ethylene; Homogeneous–heterogeneous reaction network; Rare earth catalyst; LiMgO catalyst
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Oxidative coupling of methane: catalytic behaviour assessment via comprehensive microkinetic modelling
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volumes 150–151, 5 May 2014, Pages 496–505
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
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Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
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