Characterization of Catalysts Derived from Oxidation of RuxThy Intermetallics

Article abstract of DOI:10.1021/j100380a041

Ru methanation catalysts derived from oxidation of RuxThy 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 deg C.ESCA and ISS Ru/Th intensity ratio measurements showed that surface segregation of ThO2 occurred for all catalysts.The structure of the intermetallic-derived (IM) catalysts can best be described as Ru particles embedded in a ThO2-rich overlayer.Comparison of hydrogen and CO uptake with N2 BET surface area suggests that CO more accurately titrates surface Ru than does hydrogen.Extensive spillover of hydrogen from Ru to ThO2 was also observed for all IM catalysts.The catalysts were tested for CO hydrogenation; exceptionally high methane selectivity was observed for all catalysts.On the basis of CO chemisorption, the CO hydrogenation turnover frequency was comparable for all the IM catalysts.The CO hydrogenation activities and selectivities are discussed on the basis of the structure sensitivity of CO hydrogenation on Ru catalysts and the special morphology of the IM catalysts.