Selective Production of Acetylene from the C─C Coupling Reaction of CH4 with CO2 Mediated by Ta2O2 + Cluster Cations.

Coconversion of methane and carbon dioxide to C2 hydrocarbons via the CCH4─CCO2 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 CCH4─CCO2 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 CCH4─CCO2 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.