The Active State of Supported Ruthenium Oxide Nanoparticles during Carbon Dioxide Methanation

Ruthenium catalysts supported on TiO₂ have been shown to have competitive activity and selectivity for the methanation of CO₂. In particular, a catalyst using preformed RuO₂ nanoparticles deposited on a TiO₂ support showed competitive performances in a previous study. In this work, ambient-pressure X-ray photoelectron spectroscopy was employed to determine the chemical state of this catalyst under reaction conditions. The active state of ruthenium was found to be the metallic one. Surface adsorbates were monitored in the steady state, and CH_x species were found to be favored over adsorbed carbon monoxide at increasing temperatures.