Impact of varied zeolite materials on nickel catalysts in CO2 methanation.

[Display omitted] • Mesopores in BEA catalysts facilitate small Ni particle formation. • Small Ni species boost the conversion of CO 2 to CO. • Larger Ni species promote the conversion of CO 2 to methane. • Ni-5A and Ni-13X, with larger Ni particles externally, demonstrate heightened CO 2 methanation activity. • TOF- CO2 and TOF- CH4 show a correlation with Ni particle size up to 8.8 nm. Ni catalysts supported on 4A, 5A, 13X, ZSM-5, and BEA zeolites were prepared using the vacuum-heating method for CO 2 methanation. These support materials play a pivotal role in shaping the catalysts' properties and their catalytic performance. High-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectroscopy (EDS) mappings suggest a significant concentration of Ni nanoparticles situated on the external surfaces of catalysts with low Si/Al ratios zeolites (Ni-4A, Ni-5A, and Ni-13X). These Ni nanoparticles exhibit characteristics of weaker metal-support interaction, lower metal reduction temperatures, and moderate H 2 adsorption activity. Moreover, these low Si/Al ratio zeolites demonstrate robust CO 2 adsorption activity. These properties endow Ni-5A and Ni-13X catalysts with heightened CO 2 conversion (70.4–70.9%) and methane selectivity (92.4–96.4%). In contrast, high Si/Al ratio zeolite-based catalysts (Ni-ZSM-5 and Ni-BEA) exhibit smaller Ni particles, strong metal-support interaction and weaker CO 2 adsorption activity, resulting in reduced CO 2 methanation activity and decreased methane selectivity (71.2–73.4%). The normalized CO 2 conversion rate presents a correlation with the average Ni particle size. [ABSTRACT FROM AUTHOR]