Investigation on the activity of Ni doped Ce0.8Zr0.2O2 for solar thermochemical water splitting combined with partial oxidation of methane

• Published in: International journal of hydrogen energy 2024-04, Vol.62, p.1077-1088
• Main Authors: Liu, Yanxin, Gu, Tingting, Bu, Changsheng, Liu, Daoyin, Piao, Guilin
• Format: Article
• Language: English
• Subjects: Ce0.8Zr0.2O2; H2O splitting; Ni-doping; Partial oxidation of methane; Thermochemical cycle
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2024.03.124

The incredible potential of metal oxide-based two-step solar-driven thermochemical water splitting technology lies in its ability to harness limitless solar energy to produce clean and renewable hydrogen fuel. However, achieving high redox kinetics and lowering the reaction temperature remain the primary challenges in hydrogen production. The CeO2–ZrO2 system is a well-known oxygen carrier for thermochemical water splitting on account of its high temperature stability, quick kinetics, and redox cyclability. While recent studies have explored the combination of methane partial oxidation with metal oxide reduction, the reduction effect of cerium-zirconium oxide is relatively low, and reactivity still needs improvement. The nickel-doped system exhibits good redox performance and is regenerative. In this study, different mass percentages nickel-loaded oxygen carriers mNi/Ce0.8Zr0.2O2 (m = 0, 1, 3, 5, 7, 9) were prepared using the impregnation method. Redox properties of oxygen carriers were investigated in a fixed bed reactor and various characterizations were performed. To assess the durability of mNi/Ce0.8Zr0.2O2, 60 long-cycle experiments were also conducted. The results indicate that the lattice oxygen in mNi/Ce0.8Zr0.2O2 exhibits remarkable selectivity for the partial oxidation of CH4 at temperatures ranging from 880 to 925 °C. The best reactivity performance was achieved with a nickel loading ratio of 5 wt%, and after 60 consecutive redox cycles, 5Ni/Ce0.8Zr0.2O2 demonstrates remarkable robustness, maintaining its redox activity. •mNi/Ce0.8Zr0.2O2 demonstrates excellent redox reactivity at 900 °C.•Introduction of Ni loading leads to an increase of 60% in fuel generation.•Reduction time of 5Ni/Ce0.8Zr0.2O2 is reduced by 32% compared to Ce0.8Zr0.2O2.•5Ni/Ce0.8Zr0.2O2 exhibited the most superior redox activity.