Synergy between Brønsted Acid Sites and Cu/Zn Single-Atom Sites in Zeolite for the Direct Oxidation of Methane

The direct oxidation of methane to liquid oxygenates is challenging due to the high C–H bond activation barrier. While metal sites in zeolites are typically considered the primary active centers, this study reveals that Brønsted acid sites (BAS) are indispensable for CH 4 activation. Atomic-level incorporation of Cu and Zn into ZSM-5 tunes Brønsted acid strength and stabilizes the framework, creating a cooperative acid-metal environment that enables a remarkable C1 oxygenates productivity of 41651 μmol g cat. –1 h –1 with nearly 90% selectivity at 70 °C. Through CH 4 -DRIFTS, in situ EPR, and DFT calculations, we demonstrate that BAS induce polarization of CH 4, while Cu and Zn activate H 2 O 2 to generate •OH and •OOH radicals. The •OH radicals cleave polarized CH 4 to form •CH 3 radicals, which selectively couple with reactive oxygen species to yield CH 3 OH and HCOOH. This work highlights the critical acid-metal synergy in metal-zeolite catalysts for efficient CH 4 valorization under mild conditions.