Effective CO2 methanation over site-specified ruthenium nanoparticles loaded on TiO2/palygorskite nanocomposite.

Site-specified RuO 2 nanoparticles on the TiO 2 /palygorskite matrix can be prepared through a simple pH adjustment in aqueous conditions. The product showed very good catalytic CO 2 methanation performance (upto 88% efficiency and ∼100% CH 4 seletivity) and very high stability after 60h tests at 450 °C. [Display omitted] • Site-specified RuO 2 nanoparticles on the TiO 2 /palygorskite matrix was prepared by strong electrostatic absorption route. • Palygorskite with abundant hydroxyl groups significantly disperses the Ru species and yielded very fine nanoparticles. • Excellent catalytic CO 2 methanation performance (up to 88% efficiency and ∼100% CH 4 selectivity) were reached. • The product showed very high stability after 60 h catalytic tests at 450 °C. Here a site-specifically assembled Ru nanoparticles (2–8 nm) on palygorskite (Pal) loaded TiO 2 catalyst (TiO 2 /Pal) is reported to trigger the CO-radical mediated CO 2 methanation reactions. The catalyst was prepared by the strong electrostatic adsorption (SEA) method based on the interactions between the metal source and the TiO 2 support, which have successfully prevented the Ru nanoparticles (NPs) from aggregation. The optimized Ru(4%)-TiO 2 /Pal sample showed fairly good catalytic activities (μ max = 88.7%) to CO 2 and selectivity of CH 4 (C max ∼ 100%). The catalyst also demonstrated excellent stability: no obvious decedent in CO 2 conversion and no carbon deposition were detected after 60 h methanation test. In situ FTIR measurement showed the CO species were an intermediate state, which reacted with the adsorbed hydrogen to produce hydro carbonate, bidentate or monodentate formate species, and finally reached the methane molecular. The SEA method has proven to be an effective way to produce site-specified nano-composites under delicately controlled conditions. Nanofibrous Pal acted as TiO 2 carrier and separator, surface hydroxyls supplier, and origin of repulsive force to the Ru species, which finally resulted in outstanding catalytic performance. [ABSTRACT FROM AUTHOR]