Efficient and selective oxidation of methane to oxygenates on atomically dispersed Rh catalysts promoted by carbon monoxide

The direct conversion of methane into valuable chemicals under mild conditions represents a promising technological pathway, yet achieving both high efficiency and selectivity remains a major challenge in catalysis. In this work, we report a rhodium catalyst atomically dispersed on ZSM-5 for catalytic conversion of methane to oxygenates using H 2 O 2 as oxidant under mild conditions. With carbon monoxide (CO) as a promoter, the catalyst achieved an oxygenates productivity of 46.8 mmol·g cat −1 ·h −1 (equivalent to 9360 mmol·g Rh −1 ·h −1 or 964.1 mol·mol Rh −1 ·h −1 ) with approximately 90.7 % overall selectivity (including liquid products and gaseous CO 2 ). The catalyst retained high activity over five recycling experiments. A combined investigation by HAADF-STEM, XAFS, and DRIFTS-CO analyses confirms that the active sites consist of atomically dispersed Rh species in a Rh 1 O 5 configuration anchored within the ZSM-5 micropores. Mechanistic studies, including controlled experiments, EPR, and in situ infrared spectroscopy, reveal that CO plays a dual role. It promotes the formation of ·OH radicals from H 2 O 2 and facilitates the activation of methane, leading to the generation of ·CH 3 species. Oxygenate products are produced via the direct coupling of ·CH 3 , ·OH, and CO molecules. This work highlights the potential of tailoring atomically dispersed metal catalysts and using CO as reactant and promoter to enable efficient methane transformation into valuable oxygenates.