Abstract
The production of acetic acid, an important industrial chemical traditionally obtained through the carbonylation of methanol using noble metal-based homogeneous catalysts, encounters challenges arising from high equipment costs and sustainability concerns. The direct liquid-phase oxidative carbonylation of methane emerges as a promising alternative, capitalizing on abundant natural gas resources and featuring a potentially mild and straightforward process. However, most catalysts proposed for this process suffer from low acetic acid yields due to the scarcity of active sites and the swift generation of C1 oxygenates, posing difficulties for subsequent carbonylation and impeding their industrial feasibility. Herein, we report a highly efficient 0.1Cu/Fe-HZ5-TF catalyst featuring exclusively mononuclear Fe and Cu anchored in the ZSM-5 channels. Under optimized conditions, the catalyst achieved an unprecedented acetic acid yield of 40.5 mmol gcat-1 h-1 at 50 °C, surpassing the previous maximum (12.0 mmol gcat-1h-1) by more than threefold. Comprehensive characterization, isotope-labeled experiments and DFT calculations reveal that the homogeneous mononuclear Fe sites are responsible for the activation and oxidation of methane, while the neighboring Cu sites play a key role in retarding the oxidation process. This synergistic action promotes C-C coupling, resulting in the efficient synthesis of acetic acid.
Q. Cheng, X. Yao, G. Li, L. Zheng, G. Li, K. Yang, A.-H. Emwas, X. Li, Y. Han, J. Gascon, Atomically Dispersed Fe-Cu Dual-Metal Sites Synergistically Boost Carbonylation of Methane, Angewandte Chemie International Edition, n/a (2024) e202411048. DOI: 10.1002/anie.202411048.
