Plasma-Enhanced CO₂ Hydrogenation over Co-Based Catalysts: Surface and Gas-Phase Insights

The electrification of chemical processes for industrial and energy applications is growing with the availability of low-cost electricity from nuclear and renewable sources. Among emerging technologies, non-thermal plasma (NTP) enables CO₂ hydrogenation to hydrocarbons by energizing electrons and promoting bond activation at low bulk temperatures. This work investigates NTP-assisted CO₂ hydrogenation over Co/Al₂O₃ and K-Co/Al₂O₃ catalysts, with the hypothesis that conversion under plasma occurs via an alternative mechanism driven by vibrational excitation, molecular dissociation, and electron–molecule collisions; in this context, Co facilitates CHₓ formation while potassium promotes C–C coupling. Surface intermediates and products were monitored using operando and in-situ DRIFTS with a custom NTP cell to compare with thermal reactions. Under thermal conditions, Co/Al₂O₃ formed bicarbonate, formate, and CO linked to CH₄ formation, while K-Co/Al₂O₃ showed additional carbonate species associated with K⁺, indicating stronger surface carbon bonding. Plasma-assisted DRIFTS revealed fewer stable intermediates on Co/Al₂O₃ but enhanced carbonate and methoxy species on K-Co/Al₂O₃. Molecular beam mass spectrometry (MBMS) was employed and complemented by computational modeling to support mechanistic insights. NTP enabled intermediate formation at low temperature, revealing alternative pathways and underscoring plasma–catalyst synergy in hydrocarbon synthesis.