“Design of a thermo-photo catalysis laboratory plant to investigate the plasmonic activation of CO2”

The rising concentration of atmospheric CO₂ poses a major environmental challenge. In this context, CO₂ valorization through catalytic methanation emerges as a promising strategy to reduce greenhouse gas emissions and promote a transition toward a low-impact energy system. This PhD thesis investigates the thermo-photocatalytic methanation of CO₂ over rhodium nanoparticles supported on mixed cerium-titanium oxides (Rh/Ce-TiOx), with a specific focus on plasmonic activation mechanisms. A dedicated laboratory-scale reaction system was designed and built to evaluate catalytic performance under controlled illumination and thermal conditions. Catalysts were synthesized via sol-gel methods and functionalized with rhodium using both wet impregnation and ball milling techniques. Structural and redox properties were characterized through advanced analytical techniques, including BET, XRD, TEM, TPR, DRS, and FT-IR DRIFT spectroscopy. The results showed a CO₂ conversion enhancement of up to 35% under light exposure, confirming the relevance of the plasmonic effect. Among the tested materials, the Ce:Ti (80:20) composition emerged as the most effective, offering superior stability and catalytic activity. FT-IR DRIFT analyses enabled the identification of reactive surface intermediates and the elucidation of reaction pathways under both dark and illuminated conditions. The study also highlighted the crucial role of structural defects and charge transfer at the metal–support interface. Overall, this research confirms the synergistic potential of thermo-photocatalysis for efficient CO₂ conversion and provides new insights for the development of sustainable catalytic systems for future energy applications.