(214h) Direct Ethane Upgrading to Propionic Acid Via CO Coupling at Room Temperature

Ethane, a major component of natural gas, represents an abundant and low-cost carbon feedstock for chemical manufacturing. However, the direct conversion of these saturated hydrocarbons into value-added chemicals remains a central challenge in catalysis due to the inertness of C–H bonds. Among various strategies, direct CO insertion into alkanes is particularly attractive for carbon chain extension but remains largely unexplored. In this talk, we present a thermally driven ethane–CO coupling process at room temperature for the selective synthesis of propionic acid. Under optimized conditions, we achieved an optimal propionic acid production rate of 120 μmol·g⁻¹·h⁻¹ and an optimal propionic acid selectivity up to ~85%, surpassing previous benchmarks for light alkane carboxylation under mild conditions. Isotopic labeling confirmed the incorporation of CO into the carboxyl group, while water served as the oxygen source for the hydroxyl group. In situ SERS and SEIRAS spectroscopy revealed that Cu₂O acts as the active site, where ethyl intermediates generated from C–H activation couple with Cu–CO species to form the product. Control experiments and UV–vis spectroscopy further supported the in situ generation of Cu⁺ via oxidative dissolution of Cu in acid and O₂ facilitating CO activation. This work introduces a new platform for selective C–C coupling from inert alkanes, offering mechanistic insights and practical relevance for upgrading natural gas components into value-added carboxylic acids.