Selective Production of Acetylene from the C─C Coupling Reaction of CH ₄ with CO ₂ Mediated by Ta ₂ O ₂ ⁺ Cluster Cations

Coconversion of methane and carbon dioxide to C₂ hydrocarbons via the C_CH4─C_CO2 coupling reaction is of great significance to mitigate greenhouse effect and develop an alternative route for manufacture of important industrial feedstocks (e.g., C₂H₂), however, it has not yet been achieved so far owing to the difficulty in breaking both of the C═O bonds in CO₂ as well as the precise control of sequential elementary reactions targeted for C₂ hydrocarbons. Herein, by using the tantalum oxide Ta₂O₂ ⁺ as an active cluster, an unprecedented C_CH4─C_CO2 coupling reaction of CH₄ with CO₂ to exclusively produce the C₂ hydrocarbon of C₂H₂ has been successfully realized even at room temperature by the state-of-the-art mass spectrometry. The in situ reconstruction from Ta─O─Ta cluster skeleton to tantalum carbide Ta─C─Ta experienced upon the prereaction with CH₄ is critical to delicately control the sequential elementary reactions targeted for C₂H₂ generation. This finding not only leads to a breakthrough in the field of gas-phase and condensed-phase chemistry wherein the C₂₊ oxygenated compounds were the mainstream products for C_CH4─C_CO2 coupling of CH₄ with CO₂, but also explores a new active structure and a novel reaction mechanism beneficial for selective production of C₂ hydrocarbons from coconversion of CH₄ and CO₂.