Methane coupling reaction in an oxy-steam stream through an OH radical pathway by using supported alkali metal catalysts

Yin Liang, Zhikao Li, Mohamed Nourdine, Salman Shahid, Kazuhiro Takanabe

Research output: Contribution to journalArticleResearchpeer-review

19 Citations (Scopus)

Abstract

A universal reaction mechanism involved in the oxidative coupling of methane (OCM) is demonstrated under oxy-steam conditions using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from a H 2O-O2 reaction followed by C-H activation in CH 4 with an OH radical. Thus, the presence of water enhances both the CH4 conversion rate and the C2 selectivity. This OH radical pathway that is selective for the OCM was observed for the catalyst without Mn, which suggests clearly that Mn is not the essential component in a selective OCM catalyst. The experiments with different catalyst compositions revealed that the OH.-mediated pathway proceeded in the presence of catalysts with different alkali metals (Na, K) and different oxo anions (W, Mo). This difference in catalytic activity for OH radical generation accounts for the different OCM selectivities. As a result, a high C2 yield is achievable by using Na2WO4/SiO2, which catalyzes the OH.-mediated pathway selectively. Make it methane: A universal reaction mechanism involved in the oxidative coupling of methane is demonstrated under oxy-stream conditions by using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from an H2O-O2 reaction, followed by C-H activation in CH4 with an OH radical.

Original languageEnglish
Pages (from-to)1245-1251
Number of pages7
JournalChemCatChem
Volume6
Issue number5
DOIs
Publication statusPublished - May 2014
Externally publishedYes

Keywords

  • alkali metals
  • kinetics
  • oxidative coupling
  • radicals
  • reaction mechanisms
  • supported catalysts

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