Frustrated Lewis pairs promote selective methane oxidation over ZSM-5 supported Au-WO3 photocatalyst

Selective oxidation of methane to high value-added chemicals by artificial photosynthesis offers an energy-efficient strategy for the sustainable chemical industry. However, activation of CH₄ remains a great challenge due to the inert CH bond, bringing on a low efficiency and selectivity of high-valued oxygenate product, which limits the commercial application of this technology. Herein, frustrated Lewis pairs (FLPs) as active sites were precisely fabricated over Au-WO₃ loaded ZSM-5 (AuW-ZSM-5) catalysts for the activation of CH₄. Compared to other samples, FLPs-enriched Au_0.1W_0.58-ZSM-5 enable the efficient additive-free selective CH₄ oxidation to high valued oxygenate liquid product (CH₃OH, HCOOH, CH₃COOH) with a yield of up to 139.72 µmol g^-1 h^-1 and a selectivity of 98.2 %. In-situ DRIFT and EPR studies revealed the mechanism and approach of CH₄ activation by FLPs on the AuW-ZSM-5 catalyst. It was found owing to steric encumbrance FLPs facilitate the generation of weakly bonded ·CH₃ and ·OH radicals from water dissociation and methane activation under simulated solar light, which then significantly improved the generation of primary oxygenate liquid product by radical reactions and suppress over oxidation. This finding provides new insight into the construction of FLPs and a new perspective on the activation of CH₄.