Engineering core–shell-structured BaAl₂O₄ overlaid Ni catalyst with strong metal-support interaction for durable and efficient CH₄ dry reforming

Dry reforming of methane (DRM) over Ni-based catalysts is an economically reasonable technology for large-scale CO₂ utilization. However, prolonged Ni sintering and carbon deposition reduce the durability and efficiency of DRM, hindering its engineering application. Herein, we propose a facile approach by combining continuous microscale coprecipitation with solid-state reactions to construct a BaAl₂O₄-overlayer-confined Ni catalyst. The 5- wt%-Ni@BaAl₂O₄ catalyst exhibited advanced CO₂ and CH₄ conversions of 96% and 86% at 800 °C and a GHSV of 144 L g_cat.⁻¹ h⁻¹. Moreover, the k_d-CO₂ and k_d-CH₄ of Ni@BaAl₂O₄ were 0.0063 and 0.0029 h⁻¹; which are approximately half and one-thirds of those of Ni/BaAl₂O₄ and slightly better than those of Ni@MgAl₂O₄, underscoring the versatility of the proposed synthesis protocol for constructing core–shell structures. XAS, HAADF–STEM–EDS, and CO transmission-IR characterizations confirmed the SMSI of ∼2-nm amorphous BaAl₂O₄-overlaid ∼10 nm Ni with an overall mesoporous structure. After a long-term test, the sintering and coking inhibition effects of Ni@BaAl₂O₄ (10 → 11 nm, 0.55 mg_C g_cat.⁻¹ h⁻¹) outperformed Ni/BaAl₂O₄ (13 → 22 nm, 1.90 mg_C g_cat.⁻¹ h⁻¹) and Ni@MgAl₂O₄. In situ time-resolved CH₄ → CO₂ transient response, DRIFTS experiments, and DFT calculations suggested that Ni@BaAl₂O₄ and Ni/BaAl₂O₄ followed the Mars–van Krevelen and Langmuir–Hinshelwood redox mechanisms, respectively. The functional interfacial lattice oxygen promoted the removal of C_ads* on Ni and core–shell structure induced fast CO₂ adsorption and CO desorption. The present study provides a facile approach for constructing a stable and active Ni-based core − shell catalyst. Furthermore, it offers novel insights into the functionalities of non-reducible spinel overlayers in the DRM process.