Issue 28, 2025

Direct conversion of methane to value-added hydrocarbons using alkali metal-promoted cobalt catalysts

Abstract

The oxidative coupling of methane (OCM) is a promising pathway for directly converting methane into higher hydrocarbons (C2+). This research investigated the influence of alkali metal promoters (Li, Na, K, or Rb) on Co/Al2O3 catalysts prepared based on incipient wetness impregnation for the OCM reaction. The catalyst investigations demonstrated that the catalysts promoted with K and Rb had superior performance, with the 4.6K–Co/Al2O3 catalyst achieving a maximum C2+ yield of 8.1%, C2+ selectivity of 24.0%, and CH4 conversion of 32.1% at 640 °C. Catalyst characterization, based on XRD, HR-TEM, BET, XPS, CO2-TPD, and H2-TPR analyses, revealed the structural and physicochemical properties responsible for the enhanced catalytic activity. Specifically, K and Rb promoters increased surface basicity and enhanced the electron density of active sites, thereby promoting selective methane activation. In-situ DRIFTS and mechanistic studies highlighted the role of reactive oxygen species in promoting C2+ hydrocarbon formation. These results should position K–Co/Al2O3 as a promising catalyst for OCM and provide valuable guidance for designing more efficient catalytic systems for methane utilization.

Graphical abstract: Direct conversion of methane to value-added hydrocarbons using alkali metal-promoted cobalt catalysts

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Article information

Article type
Paper
Submitted
07 Apr 2025
Accepted
30 Jun 2025
First published
07 Jul 2025
This article is Open Access
Creative Commons BY license

RSC Adv., 2025,15, 23103-23114

Direct conversion of methane to value-added hydrocarbons using alkali metal-promoted cobalt catalysts

S. Sringam, P. Thansiriphat, T. Witoon, W. Donphai, M. Chareonpanich, C. Wattanakit, H. Sohn, N. Yigit, G. Rupprechter and A. Seubsai, RSC Adv., 2025, 15, 23103 DOI: 10.1039/D5RA02408K

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