C-H bond activation on metals supported over CNT and ZrO2 for the acetic acid formation via methane and carbon dioxide reaction

This work presents C H bond activation on CuCo and Zn-based catalyst metals supported on carbon nanotubes and zirconia for acetic acid, with emphasis on CH 4 activation and subsequent CO 2 insertion leading to acetic acid formation. Catalysts were synthesized by dry impregnation and characterized by XRD, Raman spectroscopy, N 2 physisorption, and TGA. H 2 -TPR revealed metal–support interactions and reducibility that directly influence the formation of surface intermediates. CH 4 -TPSR experiments demonstrated that Cu- and Co-containing catalysts promote homolytic C H cleavage at substantially lower temperatures than Zn-based systems, enabling earlier formation of CHx species. DRIFTS measurements confirmed that CH 4 exposure generates CH x species, while the subsequent addition of CO 2 leads to the formation of carbonate, bicarbonate, formate, and acetate-type species. The CNTs evidenced that the in situ generated CO 2 enhanced the insertion into CHx fragments, thereby promoting C C bond formation. DRIFTS confirm the carboxylation pathway in the temperature range where simultaneous CH 4 activation occurs, with CO 2 availability and H 2 . Post-reaction characterization shows preservation of the active sites, phases, and carbon formation associated with CH 4 activation. This work confirms the methane carboxylation pathway and highlights the catalytic relevance of the reaction with CO 2 to enable C C coupling under milder conditions.