Hydroxyl-Promoted C─C Coupling for Selective Methane Conversion into Ethane on Cerium Oxide Photocatalyst

Area of Science:

• Catalysis
• Materials Science
• Green Chemistry

Background:

• Converting methane to valuable chemicals offers environmental and energy advantages but faces challenges in C-H bond activation and over-oxidation.
• Noble-metal-free photocatalysts are sought for sustainable chemical synthesis, yet their efficiency in methane valorization remains limited.

Purpose of the Study:

• To investigate the role of hydroxyl-rich surfaces on noble-metal-free photocatalysts in directing selective methane C-C coupling.
• To elucidate the mechanism by which surface hydroxyls enhance methane conversion and suppress over-oxidation.
• To develop a sustainable and efficient photocatalytic system for continuous ethane production from methane.

Main Methods:

• Utilized noble-metal-free photocatalysts modified with hydroxyl-rich surfaces.
• Employed a flow-reactor system under ambient conditions for methane conversion experiments.
• Analyzed catalytic performance, including ethane production rate and selectivity, over extended operation periods.

Main Results:

• Hydroxyl-rich surfaces were demonstrated to be pivotal in directing selective C-C coupling of methane.
• Surface hydroxyls enhanced methane chemisorption, improved charge separation, and facilitated favorable interactions with oxygen.
• The catalyst achieved a continuous ethane production rate of 187 µmol·g^-1·h^-1 with 97% selectivity over 200 hours, outperforming previous systems.

Conclusions:

• Hydroxyl-modified surfaces play a critical role in methane valorization by lowering activation barriers and preventing over-oxidation.
• This study provides crucial insights into designing efficient noble-metal-free photocatalysts for sustainable methane conversion.
• The developed system offers a promising pathway for the environmentally friendly production of high-value chemicals from methane.