Noble metal ionic sites for catalytichydrogen combustion: spectroscopic insights

Abstract

A catalytichydrogen combustion reaction was carried out over noble metal catalysts substituted in ZrO₂ and TiO₂ in ionic form. The catalysts were synthesized by the solution combustion technique. The compounds showed high activity and CO tolerance for the reaction. The activity of Pd and Pt ion substituted TiO₂ was comparable and was higher than Pd and Pt ion substituted ZrO₂. The mechanisms of the reaction over the two supports were proposed by making use of the X-ray photoelectron spectroscopy and FT infrared spectroscopic observations. The reaction over ZrO₂ supported catalysts was proposed to take place by the utilization of the surface hydroxyl groups while the reaction over TiO₂ supported catalysts was hypothesized to be a hybrid mechanism utilizing surface hydroxyl groups and the lattice oxygen.