One-step synthesis of Ni/CeO2 catalyst with fine structure for CO2 methanation by flame-assisted spray pyrolysis

CO 2 methanation is attracting attention as a synthetic fuel manufacturing process using hydrogen from renewable energy. The large-scale implementation of methanation in society requires the development of high-performance, stable catalysts and the establishment of methods for their mass production. In this study, Ni/CeO 2 catalyst is prepared using flame-assisted spray pyrolysis (FASP), which is a one-step and rapid process for producing fine particles, and the detailed particle structure and CO 2 methanation performance are evaluated. The results are also compared with those of catalysts prepared by the conventional impregnation method (IM). The FASP catalyst consists mainly of particles ranging from 10–20 nm in size, with some particles reaching several hundred nanometers, while IM catalyst consists of micrometer-sized CeO 2 particles with approximately 30 nm-Ni particles on the surface. The FASP catalyst also shows higher specific surface area and Ni dispersion than the IM catalyst. Furthermore, XAFS, XPS, and H 2 -TPR analyses suggests that FASP promotes the formation of oxygen vacancies, Ni-O-Ce interfacial sites, and reduced Ni species. In CO 2 methanation tests, the FASP catalyst exhibits higher CO 2 conversion and CH 4 selectivity than the IM catalyst, achieving a CH 4 production rate of 81.3 µmol/(g cat ·s) at 300 °C, which is high-level among the literature values. These suggest that the fine particle structure, abundant oxygen vacancies and reduced Ni species, and increased Ni-CeO 2 interfaces formed by FASP contribute to the enhanced catalytic activity. This study demonstrates that FASP is a promising method for the simple production of highly active CO 2 methanation catalysts with fine structure.