Mechanistic study of catalytic CO₂ hydrogenation in a plasma by operando DRIFT spectroscopy

Plasma-enhanced heterogeneous catalysis offers a promising alternative to thermal catalysis for many industrially relevant processes. There is only limited mechanistic understanding about the relation between the interactions of highly energetic electrons and excited molecules with heterogeneous catalysts in a plasma and their catalytic performance. Herein, a novel operando infrared spectroscopy cell is presented allowing the investigation of surface intermediates upon exposure of a catalyst to plasma. The polyether ether ketone cell enclosure embedding a quartz reactor is operated at atmospheric pressure and can be heated to 250 °C. A case study involved the characterization of surface intermediates during CO2 hydrogenation on a Co/CeZrO4 catalyst. The temperature was monitored using online UV-Vis spectroscopy. This combined approach offers new experimental insights into plasma-catalyst synergy. The most important one is the demonstration of CO2 methanation at the catalyst surface at room temperature in a plasma.