[2P01-29] Poster session

[2P10] In-situ observation of a Cu-Zn/Al₂O₃ catalyst during CO₂ hydrogenation conditions using fluorescence-yield dispersive soft X-ray absorption spectroscopy

*Daiki Kanesada¹, Kota Enomoto¹, Fumitoshi Kumaki^1,2, Ryo Toyoshima³, Yuki Tsujikawa², Kaoruho Sakata², Kenta Amemiya², Hiroshi Kondoh¹ (1. Keio University (Japan), 2. KEK-IMSS (Japan), 3. The University of Tokyo (Japan))

Methanol synthesis from CO₂ hydrogenation is crucial for achieving carbon neutrality, but the active sites of Cu-Zn/Al₂O₃ catalysts remain controversial. In this study, the chemical state changes of copper were investigated by in-situ fluorescence-yield dispersive soft X-ray absorption spectroscopy (FY-DsXAS) under near-ambient-pressure CO₂ and H₂ gas conditions. The catalyst sample was pre-reduced by heating in a H₂ atmosphere, turning the initial Cu²⁺ state into Cu⁰. Under a mixed gas of CO₂ (5 Torr) and H₂ (10 Torr), partial oxidation from Cu⁰ to Cu⁺ was observed from 200℃ to 275℃, whereas a reduction from Cu⁺ to Cu⁰ occurred from 275℃ to 300℃. A similar oxidation behavior was also observed under CO₂ gas alone, indicating that this oxidation originates from the dissociation of CO₂. Furthermore, this transient Cu⁺ formation was not observed during subsequent CO₂ and H₂ refill and re-heating. We will discuss this transient oxidation and the catalytic activity.

Password required to view