The Dual-Active-Site Catalysts Containing Atomically Dispersed Pr3+ with Ni/CeO2 for CO2 Hydrogenation to Methane

Abstract

In this study, uniformly dispersed Pr3+ as an isolated atom over Ni/CeO2 catalyst (Ni-Pr/CeO2) is designed to enhance catalytic activity for CO2 methanation, achieving an impressive 87% conversion with ≈100% CH4 selectivity at 300 °C temperature. In contrast, the traditional Ni/CeO2 and NiPr/CeO2-imp catalysts exhibit poor conversion and selectivity, highlighting the proof of concept on the advantage of atomic-scale dispersion. Structural analysis via PXRD, XAS, and XPS confirms the successful incorporation of Pr3+ into the CeO2 lattice by creating defects. XPS and XAS studies further reveal a significant increase in oxygen vacancies, a key factor in enhancing catalytic performance at lower reaction temperatures. STEM-EDS analysis confirms the ultra-dispersion of Pr3+ (≈7 wt.%) over CeO2, ensuring a highly active catalyst surface. H2-TPR and CO2-TPD results suggest that the Pr3+ doping enhances the catalytic activity by decreasing the reduction temperature and increasing basic sites. Additionally, long-term stability tests demonstrate no significant loss in activity over 40 h, confirming the catalyst's robustness and recyclability. This work provides critical insights into the structure-activity relationship of Pr3+-modified Ni/CeO2 catalysts, emphasizing the role of oxygen vacancies in optimizing CO2 hydrogenation efficiency. © 2025 The Author(s). Small published by Wiley-VCH GmbH.