posted on 2023-01-02, 17:34authored byChunyang Dong, Maya Marinova, Karima Ben Tayeb, Olga V. Safonova, Yong Zhou, Di Hu, Sergei Chernyak, Massimo Corda, Jérémie Zaffran, Andrei Y. Khodakov, Vitaly V. Ordomsky
Direct functionalization of methane selectively to value-added
chemicals is still one of the main challenges in modern science. Acetic
acid is an important industrial chemical produced nowadays by expensive
and environmentally unfriendly carbonylation of methanol using homogeneous
catalysts. Here, we report a new photocatalytic reaction route to
synthesize acetic acid from CH4 and CO at room temperature
using water as the sole external oxygen source. The optimized photocatalyst
consists of a TiO2 support and ammonium phosphotungstic
polyoxometalate (NPW) clusters anchored with isolated Pt single atoms
(Pt1). It enables a stable synthesis of 5.7 mmol·L–1 acetic acid solution in 60 h with the selectivity
over 90% and 66% to acetic acid on liquid-phase and carbon basis,
respectively, with the production of 99 mol of acetic acid per mol
of Pt. Combined isotopic and in situ spectroscopy
investigation suggests that synthesis of acetic acid proceeds via
a photocatalytic oxidative carbonylation of methane over the Pt1 sites, with the methane activation facilitated by water-derived
hydroxyl radicals.