イオン・電⼦混合伝導体によるCO2還元反応の加速効果 −資源制約を考慮した⾼性能酸素キャリア材料の設計と合成−

2026-06-11 東京科学大学

図1. （a）ケミカルルーピングCO₂還元システムの概念図と（b）鉄置換チタン酸カルシウム(CTFO)によるCO₂還元反応加速機構のイメージ図

＜関連情報＞

• https://www.isct.ac.jp/ja/news/eadaplen4fuq#top
• https://www.sciencedirect.com/science/article/abs/pii/S1385894726039161

混合イオン伝導体と電子伝導体を用いた化学ループ式CO2分解における金属酸化物酸化還元反応の協調的促進 Cooperative enhancement of the metal oxide redox reaction in chemical looping CO2 splitting using a mixed ionic and electronic conductor

Takayuki Kosaka, Arufa Shiota, Junichiro Otomo
Chemical Engineering Journal  Available online: 20 April 2026
DOI:https://doi.org/10.1016/j.cej.2026.176455

Highlights

• Fe-doped CaTiO₃ was investigated as a support of Fe in chemical looping.
• Fe oxidation by CO₂ was enhanced with Fe-doped CaTiO₃.
• 100% CO selectivity was confirmed by a fluidized bed reactor.
• The enhancement is attributed to mixed ionic and electronic conductivity.
• Concentration of electron and oxygen vacancy may be related to the rate constants.

Abstract

Chemical looping CO₂ splitting reduces CO₂ to CO in an oxidation reaction coupled with a subsequent reduction reaction of metal oxides. This study demonstrated that calcium titanate (CaTiO₃), a non-rare earth perovskite that exhibits mixed ionic and electronic conductivity on substitution of Ti by Fe, substantially enhances CO₂ splitting. Fe-doped CaTiO₃ exhibits high electronic conductivity (10^–1.2 S cm⁻¹ at 900 °C) and ionic conductivity (10^–1.8 S cm⁻¹ at 900 °C) at the oxygen partial pressure at which CO₂ splitting by Fe oxidation occurs (p_O2 = 10⁻¹⁷–10⁻¹⁶ atm). Kinetic analysis showed that Fe-doped CaTiO₃ enhances CO₂ splitting more effectively than a pure oxide ion conductor or an insulator. This is attributed to the cooperative effects of metal oxidation and the high ionic and electronic conductivities of the support at p_O2 = 10⁻¹⁷–10⁻¹⁶ atm, as well as oxide ion and electron conduction at the metal–support interface. The increase in the concentration of electron as well as oxygen vacancy on the substitution of Ti in CaTiO₃ by Fe likely contributes to the increase in the kinetic constant of CO₂ splitting. These findings provide insights into the design of support materials and metal redox reactions.