Characterization of catalysts derived from oxidation of ruthenium-thorium intermetallics

Ru methanation catalysts derived from oxidation of Ru{sub x}Th{sub y} intermetallics were characterized by X-ray photoelectron spectroscopy (ESCA), ion scattering spectroscopy (ISS), X-ray diffraction (XRD), BET surface area measurements, chemisorption, and gravimetric analysis. XRD measurements and gravimetric analysis indicated that all intermetallics were extensively decomposed by oxidation in air at 350{degree}C. ESCA and ISS Ru/Th intensity ratio measurements showed that surface segregation of ThO{sub 2} occurred for all catalysts. The structure of the intermetallic-derived (IM) catalysts can best be described as Ru particles embedded in a ThO{sub 2}-rich overlayer. Comparison of hydrogen and CO uptake with N{sub 2} BET surface area suggests that CO more accurately titrates surface Ru than does hydrogen. Extensive spillover of hydrogen from Ru to ThO{sub 2} was also observed for all IM catalysts. On the basis of CO chemisorption, the CO hydrogenation turnover frequency was comparable for all the IM catalysts.