Co-oxidation of methane (CH 4 ) and carbon disulfide (CS 2

Zhe Zeng, Bogdan Z. Dlugogorski, Ibukun Oluwoye, Mohammednoor Altarawneh

Research output: Contribution to journalArticle

Abstract

Sulfur-containing species persist as important impurities in fossil fuels, affecting the combustion process of constituent hydrocarbons. This contribution reports the promotion effects of carbon disulfide (CS 2 ) on oxidation of methane (CH 4 ), with experiments conducted in a jet-stirred reactor (JSR), and explains the experimental findings from comprehensive kinetic modelling of CH 4 /CS 2 /O 2 systems. This includes neat oxidation of CH 4 /O 2 and CS 2 /O 2 under stoichiometric conditions, as compared with co-oxidation of CH 4 /CS 2 /O 2 , containing different measures of CS 2 . Addition of small amounts of CS 2 (50?ppm and 100?ppm) enhances the oxidation of CH 4 (500?ppm) as characterised by a lower onset temperature (1300?K versus 1200?K and 1060?K). In contrast, the presence of CH 4 delays the process of CS 2 oxidation. Considering the similarity in the core charge of O and S, we propose the reactivity of S 2 , SO and in particular S towards CH 4 to be responsible for the observed behaviours, in addition to an important effect of O radicals generated in oxidation of CS 2 on engendering the oxidation of CH 4 . As reported in the literature, in analogy to O 2 and O which oxidise CH 4 into CO 2 , the S/S 2 /SO could also 'sulfurdise' CH 4 into CS 2 or COS under oxygen-lean conditions. Quantum chemistry calculations of the CH 4 ?+?O, CH 4 ?+?S, CH 4 ?+?S 2 , CH 4 ?+?SO and CH 4 ?+?O 2 reactions further reveal the reactivity of O, O 2 , S, S 2 and SO towards H abstraction from CH 4 . The sensitivity analysis of the kinetic modelling of the proposed co-oxidation reactions indicates that, the radicals formed during the CS 2 conversion process promote the oxidation of CH 4 at lower temperatures. However, the consumption of radicals in the CH 4 oxidation also inhibits the decomposition of CS 2 as observed in the experiments.

Original languageEnglish
Pages (from-to)677-685
Number of pages9
JournalProceedings of the Combustion Institute
Volume37
Issue number1
Early online date29 Aug 2018
DOIs
Publication statusPublished - 1 Jan 2019
Externally publishedYes

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