Non-isothermal reduction kinetics and mechanisms by hydrogen of CuAl spinel solid solution

• Published in: Catalysis communications Vol. 173; p. 106570
• Main Authors: Liu, Ya-Jie, Kang, He-Fei, Zhang, Liang-Liang, Xue, Cai-Long, Yuan, Li-Jing, Hou, Xiao-Ning, Zhang, Lei, Gao, Zhi-Xian
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.01.2023; Elsevier
• Subjects: Cu[sbnd]Al spinel solid solution; CuAl spinel solid solution; Mechanisms; Non-isothermal; Reduction kinetics; Structure evolution; Non-isothermal; Reduction kinetics; Structure evolution; Mechanisms; CuAl spinel solid solution
• DOI: 10.1016/j.catcom.2022.106570
• ISSN: 1566-7367

The non-isothermal reduction kinetics by hydrogen of CuAl spinel solid solution was investigated using H2 temperature-programmed reduction at different heating rates methodology. The reduction process consists of four stages in terms of the reduction degree (α), corresponding to the reduction of non-spinel Cu2+, easily reducible spinel Cu2+, hardly reducible spinel Cu2+ (I), and hardly reducible spinel Cu2+ (II). The activation energy was between 83.2 and 122.1 kJ mol−1 when α < 0.72, but increased sharply to ∼500 kJ mol−1 at α = 0.95, leading to different reduction mechanisms for these Cu2+ species. Furthermore, the phase transformation, spinel structure evolution, as well as reduction mechanism were investigated. •Non-isothermal reduction kinetics of Cu-Al spinel solid solution are investigated.•The reduction process contains four stages in terms of the reduction degree.•High activation energy evidences low reducibility of hardly-reducible spinel Cu2+.•Different kinetic models are suitable to the reduction of different copper species.•Dynamic changes of both active Cu metal and Cu-Al spinel structure.