ZSM-5-confined Cr1–O4 active sites boost methane direct oxidation to C1 oxygenates under mild conditions

Abstract

Direct oxidation of methane (DOM) to value-added chemicals is of great significance but is still challenging under mild conditions. Herein, we report that Cr₁–O₄ as an active site in a ZSM-5 anchored Cr single atom catalyst (Cr₁/ZSM-5 SAC) can efficiently catalyse the DOM to form value-added C1 oxygenated products with a productivity of 21 100 μmol g_cat⁻¹ h⁻¹ and a selectivity of 99.8% at 50 °C within 30 min, which outperforms most reported state-of-the-art catalysts. Density functional theory (DFT) calculations and experimental results show that Cr₁ atoms anchored on the wall of ZSM-5 micropores form the Cr₁–O₄ active sites, which boosts the formation of the reactive oxygen species (adsorbed OH species) and the activation of a C–H bond in CH₄. We believe that our atomic-level design strategy on a non-noble metal offers an approach to rationally design efficient catalysts for methane conversion.