Boosting Formic Acid Production in Methane Oxidation by Zeolite Confined Single‐Site Rh Catalyst

Abstract

ABSTRACT The selective oxidation of methane to value‐added oxygenates remains a long‐standing challenge in catalysis, often constrained by poor reactivity (and single‐pass methane conversion) and limited product selectivity. In this study, we report a Rh‐Beta catalyst featuring atomically dispersed Rh δ+ species embedded in the aluminosilicate *BEA zeolite matrix that enables highly selective methane oxidation in a CH 4– O 2– CO–H 2 O system. This catalyst achieves a remarkable formic acid space‐time yield of 210 mol mol Rh −1 h −1 at 7.84% methane conversion, with formic acid selectivity of 96%—surpassing all previously reported catalyst systems. Mechanistic investigations combining spectroscopy and theory reveal that hydroxyl radicals, generated via acid‐promoted water‐gas shift and in situ H 2– O 2 reactions, are responsible for methane activation, while the zeolite backbone plays a vital role in stabilizing formaldehyde intermediate and promoting its further oxidation to formic acid product. This work offers a new perspective on the conversion–selectivity relationship in methane oxidation and demonstrates a feasible pathway for the selective functionalization of methane under mild conditions.