Ru nanoparticles stabilized by ionic liquids supported onto silica: highly active catalysts for low-temperature CO2 methanation

Abstract

A series of Ru-based catalysts for CO₂ methanation at low temperature were synthesized by the dispersion of Ru nanoparticles in different 1-butyl-3-methylimidazolium ionic liquids on a silica support. The effect of various ionic liquids and loadings on the physicochemical properties of the catalysts and the methanation catalytic activity were investigated. The Ru/[BMIM]BF₄(1 : 10)/SiO₂ catalyst demonstrated the best catalytic performance with CO₂ conversion of 70.47% at 250 °C, which was related to the highly dispersed small Ru nanoparticles, basic property, and readily reducible RuO₂ species. The results revealed that ionic liquids can not only be used as a protectant to effectively prevent the aggregation and oxidation of the nanoparticles by space resistance and electrostatic protection, but can also be adsorbed on the surface of Ru nanoparticles as a modification layer with strong adsorption to ultimately determine the size of the nanoparticles and maintain high dispersion, which can significantly affect the catalytic activity.